Physics Defn Pack_Revision_2012

FOR INTERNAL CIRCULATION ONLY

Updated 2012-07 Page 1 of 35 JJ 2010

JURONG JUNIOR COLLEGE H2 PHYSICS (9646)

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Note:

This document is a collection of suggested questions and solutions for explanationbased questions according to H2 Physics topical learning outcomes. The list of questions is not exhaustive and is meant as a reference only.

Students are advised to identify the keywords and modify the suggested answers according to the marks allocated if similar questions are to be attempted in the A Level Examination.



Chapter 1: Measurement

Definitions 1. All physical quantities consist of a numerical magnitude and a unit. 2. Base units are units from which all other units can be defined. 3. Derived units are units that can be expressed as the product or quotient of base units. 4. An equation is homogenous (or dimensionally consistent) if the base units of all terms are

the same. 5. Avogadro constant is the number of particles in one mole of substance. 6. One mole of any substance is the amount containing as many particles as there are atoms

in 0.012 kg of carbon-12. 7. A vector quantity consists of a magnitude and a direction. 8. A scalar quantity consists of a magnitude only. 9. Random error is one that occurs without a fixed pattern resulting in a scatter of readings

about a mean value. 10. Systematic error is one that occurs with a fixed pattern resulting in a consistent over-

estimation or under-estimation of the actual value. 11. A set of precise measurements is one that has a small spread or scatter of readings. 12. An accurate measurement is one that is close to the actual value 13. The absolute uncertainty is to be written as 1 significant figure, while the calculated

answer is to be expressed to the same number of decimal places as the uncertainty. E.g.: (12.34 0.01) kg

Sample Explanation Questions 1.

Recall the 6 base quantities and associated units. Base Quantities Unit / Symbol Length metre / m Time second / s Mass kilogramme / kg Current ampere / A Amount of substance mole / mol Temperature kelvin / K



2. Recall prefixes, its symbols and its meaning from tera to pico. Prefix Symbol Multiplying Factor tera T x 1210 giga G x 910 mega M x 610 kilo k x 310 deci d x 110 centi c x 210 milli m x 310 micro x 610 nano n x 910 pico p x 1210

3. Distinguish between systematic and random errors. Give examples. Systematic Errors Random Errors

Causes consistent deviations of the readings in one direction from its actual value.

Causes scatter of readings about a mean value.

Cannot be reduced by taking repeated readings. Can be reduced by repeated readings.

Can be eliminated by making a mathematical correction or using calibration curves. Cannot be eliminated.

Examples: zero errors, heat loss to surroundings , radioactive background count rate.

Examples: measurement of time, parallax error, imperfect materials used.

4. Distinguish between accuracy and precision. Accuracy Precision

An accurate reading is one with small systematic error.

A precise reading is one with small random error.

An accurate reading is one that is close to the actual value.

A set of precise readings is one that has a small spread or scatter of readings.

5. Distinguish between a scalar and a vector quantity, give examples for each. Scalar Quantity Vector Quantity

Has magnitude only. Has magnitude and direction. E.g.: mass, distance, speed, energy E.g.: velocity, displacement, acceleration,

momentum



Chapter 2: Kinematics

Definitions 1. Displacement The linear distance in a given direction from a reference point. 2. Speed - The rate of change of distance travelled. 3. Velocity - The rate of change of displacement. 4. Acceleration - The rate of change of velocity.

Sample Explanation Questions 1. Derive the equation = +v u at

From the definition of acceleration, v uat

= v u at= +

2. Derive the equation = + 212s ut at From the definition of velocity, average velocity = s / t

2u v s

t

+=

( )2

u vs t

+=

Combining with equation in (1): 2( ) 12 2

u u at ts ut at

+ += = +

3. Derive the equation = +2 2 2v u as

Using v uta

= , sub into equation in (2) 2 2 2v u as= +

4. Describe qualitatively the motion of bodies falling in a uniform gravitational field with air resistance. A falling object has 2 forces acting on it. Its weight acts vertically downwards. Drag force due to air resistance acts vertically upwards. Drag force increases with velocity of the object. When the drag force is equal to the weight of the object, the object is said to achieve

terminal velocity (constant velocity).



Chapter 3: Dynamics Definitions 1. Newtons First Law of Motion states that every object continues in its state of rest or

uniform motion in a straight line unless a resultant force acts on it.

2. Newtons Second Law of Motion states that for a system, the rate of change of momentum is directly proportional to the resultant force acting on it and the change occurs in the direction of that resultant force.

3. Newtons Third Law of Motion states that when object A exerts a force on object B, then object B exerts a force of the same type that is equal in magnitude and opposite in direction on body A.

4. Linear momentum of an object is the product of its mass and its velocity. 5. Impulse of a force is the integral of the force over the time interval during which the force

acts.

6. The Principle of Conservation of linear momentum states that the total momentum of a system of interacting bodies is constant provided no external resultant force acts on it.

Sample Explanation Questions 1. What is meant by mass and weight?

Mass is the property of an object which resists change in motion. Weight of an object is the gravitational force acting on it. An object placed in a gravitational field would experience a gravitational force. Weight = Mass x Acceleration due to gravity (W = mg).

2. What is force? Force is the rate of change of momentum.

3. Distinguish between Elastic and Inelastic Collision. Conservation of momentum is applicable for all types of collisions as long as there is no external resultant force acting. Conservation of kinetic energy is applicable only for elastic collision. The relative speed of approach is equal to the relative speed of separation.

4. Explain why the total momentum is conserved when the resultant force acting on the system is equal to zero? By Newtons second law, when the resultant force acting on the system is equal to zero, the rate of change of momentum is also equal to zero. Hence, total momentum is conserved.

5. Explain why in an inelastic collision between two objects, the total momentum of a system is conserved even though the total kinetic energy is not conserved. In an inelastic collision, even though the total kinetic energy is not conserved, by Newtons third law, the forces acting on the two objects are still equal and opposite, leading to an equal and opposite change in momentum. Hence the total momentum is conserved.

6. Explain what is meant by weightlessness and give an example. It is a situation where the only force acting on the person is the gravitational force. Example : A high jumper in mid-air with no air-resistance or any free-fall situation.



Chapter 4: Forces

Definitions 1. Hookes Law states that the force required to extend (or compress) an elongated object is

directly proportional to the extension (or compression), provided the limit of proportionality is not exceeded.

2. Archimedes Principle states that the upthrust acting on an object placed in a fluid is equal to the weight of the fluid displaced.

3. Principle of flotation states that, for an object floating in equilibrium in a fluid, the upthrust is equal to the weight of the object.

4. The moment of a force about a pivot is the product of that force and the perpendicular distance between the line of action of the force and the pivot.

5. The Principle of moments states that, for a body in rotational equilibrium, the total clockwise moments about any point is equal to the total anti-clockwise moments about the same point.

Sample Explanation Questions 1. What is meant by upthrust?

Upthrust is the upward vertical force exerted on an object immersed in a fluid due to the pressure difference between the upper and lower surfaces of the object.

2. State the origin of upthrust. Upthrust on an object is caused by the pressure difference between its upper and lower surfaces. This pressure difference creates a resultant upward force on the object which we call upthrust.

3. What is meant by the centre of gravity of an object? The centre of gravity of an object is the point through which the weight of the object is taken to act.

4. What is meant by couple and torque? A couple is a pair of equal but opposite forces which do not act along the same line. The torque of a couple is the product of one of the forces and the perpendicular distance between their lines of action.

5. State the conditions for an object to be in equilibrium. (a) The resultant force acting on the object is zero. (b) The resultant torque acting on the object is zero.



6. Compare qualitatively frictional forces and viscous forces including air resistance. Frictional Forces Viscous Forces

Similarities Dissipative in nature Dissipative in nature Oppose motion Oppose motion

Differences

Act along the surfaces in contact between two solid objects.

Act between a fluid and a solid/fluid.

Not affected by relative speed between the two surfaces.

Increase with the relative speed between the two surfaces.

Friction exists even when the object is at rest.

Does not exist when there is no relative motion.



u = 0 F

v

s

m

h Constant velocity, v

m

F

Chapter 5: Work, Energy and Power

Definitions 1. Work done by a force is the product of the force and the displacement in the direction of the

force.

2. The Principle of conservation of energy states that energy cannot be created nor destroyed but is transformed from one form to another.

3. Power is work done per unit time.

Sample Explanation Questions 1. Derive, from the equations of motion, the formula Ek = 12 mv

2.

Consider a situation where a constant force F acts on a stationary object of mass m. The object is displaced by a displacement s in the direction of the force. The final velocity is v.

From = +2 2 2v u as = +

2 0 2 Fv sm

F = 2

2mv

s

Using Work done on object = Fs = 2

2mv

s(s)

= 12 m v

2

Since Fs is the work done on the object, which is equal to the increase in kinetic energy (Ek - 0), hence Ek = 12 m v2

2. Derive, from the defining equation W = Fs, the formula Ep = mgh for potential energy changes near the Earths surface. Consider a situation where a force F acts on an object of mass m to move the object vertically upwards. The object is displaced at constant speed (so that no change in Ek) by a displacement h in the direction of the force. Since the object moves at constant speed, the upward force, F, must be equal to the weight of the object, mg. (no resultant force).

Using Work done on object = Fh = (mg)h

Since Fh is the work done on the object and is equal to the increase in potential energy, Ep = mgh



3. Distinguish between gravitational potential energy, electric potential energy and elastic potential energy. Gravitational potential energy arises from interaction between masses, where gravitational forces involved are always attractive in nature. Electric potential energy arises from interaction between charges, where electric forces involved can be either attractive or repulsive. Elastic potential energy arises from deformation of a material.

4. Derive power as the product of force and velocity. If work is done at a constant rate,

Power, P = time

donework =

Wt

= Fst

= Fv



Chapter 6: Thermal Physics

Definitions 1. Internal energy of a system is the sum of the random distribution of kinetic and potential

energies associated with the molecules of the system.

For Ideal Gas Internal energy of an ideal gas is the sum of the random distribution of kinetic energies associated with the molecules of the system.

2. The specific heat capacity of a substance is defined as the quantity of thermal energy per unit mass supplied to the object to cause a unit rise in temperature.

3. The specific latent heat of a substance is defined as the energy per unit mass required to cause the substance to undergo a change of state at constant temperature.

4. The first law of thermodynamics states that the increase in internal energy of a system is the sum of the heat supplied to the system and the work done on the system. The internal energy is a function of state.

Sample Explanation Questions 1. Explain why an increase in the temperature of a system is associated with a rise in

its internal energy. The mean translational kinetic energy of the molecules is proportional to the temperature. When temperature rises, mean translational kinetic energy rises, hence internal energy rises.

2. What is meant by thermal equilibrium? Two bodies are in thermal equilibrium when there is no net heat transfer between them. This implies they are at the same temperature.

3. What is meant by the absolute temperature scale? The absolute temperature scale (also known as the thermodynamic temperature scale) does not depend on any thermometric property. The two fixed points used in this scale are the absolute zero and the triple point of water. The unit of this scale is the kelvin.

4. What is the triple point of water? It is the temperature at which the saturated water vapour, pure water and ice all coexist in thermal equilibrium. (Ttr = 273.16 K). It is a unique temperature which can be precisely reproducible.

5. What is absolute zero? Absolute zero is the temperature at which all substances have a minimum internal energy. It is denoted by zero kelvin.



6. Explain using the kinetic theory of gases how gases exert pressure. Pressure exerted by a gas is due to the collision of the gas molecules with walls of the container. The collision will result in a change in momentum of the molecules due to the wall, which by Newtons 3rd law implies a force exerted on the wall by the molecules. This force acting per unit area of the container wall results in pressure. (The collisions between molecules will NOT result in any pressure change, as all collisions between molecules involve conservation of momentum and kinetic energy, hence, any gain in momentum or KE by one molecule will result in another molecule losing an equal amount of that quantity).

7. Explain using a simple kinetic model for matter why (i) melting and boiling take place without a change in temperature.

All the thermal energy supplied during melting is used to weaken intermolecular bonds and increase (slightly) the intermolecular spacing between molecules. However, the mean random KE of molecules is NOT changed, hence the temperature remains constant.

All the thermal energy supplied during boiling is used to greatly increase the separation between molecules (to change state from liquid to gas) by overcoming the intermolecular attractions and to do work against the surrounding pressure. However, the mean random KE of molecules is NOT changed, hence the temperature remains constant.

(ii) The specific latent heat of vaporization is higher than the specific latent heat of fusion for the same substance. For the same mass of substance, the energy needed during boiling is higher than during melting. Heat absorbed during boiling is used to greatly increase the intermolecular spacing between molecules by overcoming the intermolecular attractions and to do work against the surrounding pressure.

However, energy absorbed during melting is used to weaken the intermolecular bond, which is less than that required for boiling. There is also little work done against the surrounding pressure due to the slight increase in the volume. Hence, specific latent heat of vaporization is higher than specific latent heat of fusion for the same substance.

(iii) Cooling effect accompanies evaporation. Molecules in the liquid with the highest KE and lie closest to the surface have the highest probability to escape from the surface (i.e. become gas molecules). This causes the mean KE of the remaining liquid molecules to decrease. Since Temperature Mean Random KE, the temperature of the liquid decreases.



Chapter 7: Current of Electricity & D.C. Circuits

Definitions 1. Electric current is the rate of flow of electric charge. 2. Charge is the product of the electric current flowing through a cross section of a circuit and

the time of which it flows. 3. One coulomb is the quantity of electric charge that passes through a cross section of a

circuit when a steady current of one ampere flows for one second. 4. The potential difference (p.d.) between 2 points in a circuit is defined as the energy

converted from electrical to other forms of energy per unit charge passing from one point to the other.

5. One volt is the potential difference between two points in a circuit in which one joule of electrical energy is converted to other forms when one coulomb of charge passes from one point to the other.

6. The electromotive force (e.m.f.) of a source is defined as the energy converted from non-electrical to electrical per unit charge driven through the source.

7. Resistance of a resistor is defined as the ratio of the potential difference across the resistor to the current flowing through it.

8. One ohm is the electrical resistance of a resistor when a potential difference of one volt across its terminals drives a current of one ampere through it.

Sample Explanation Questions 1. Sketch and explain the I V characteristics of a metallic conductor at constant

temperature.

Obeys Ohms law. At constant temperature, current (I) is proportional to potential difference (V). Hence, resistance is constant at constant temperature.

2. Sketch and explain the I V characteristics of a tungsten filament lamp.

Does not obey Ohms law. current increases at a decreasing rate with increasing potential difference (p.d.) Resistance increases as applied potential difference increases.



Reason for characteristics: When applied potential difference increases, current increases and temperature of the

tungsten filament increases. This causes the lattice ions in the metal to vibrate more vigorously, causing an

increased rate of collision with the moving electrons. The increased rate of collision reduces the rate of flow of electrons, hence, lowering the

current flow. This is thus seen as an increase in resistance of the material.

3. Sketch and explain the I V characteristics of a semiconductor diode.

Does not obey Ohms law.

(i). Forward biased current increases at an increasing rate with increasing potential difference (p.d.) Resistance decreases as applied potential difference increases.

Reason for characteristics: When applied potential difference increases, current increases and temperature

of the diode increases. This causes an increase in the number of charge carriers (electron-hole pairs) in

the semiconductor. The effect is an increase in the rate of flow of charge carriers, and results in a

decrease in resistance. Although there is also an increase in the rate of collision with the lattice ions

which would increase the resistance, this effect is not as dominant. Hence, the overall effect of increase in temperature is a decrease in resistance.

(ii). Reverse biased no current flows. Refer to the topic Semiconductors.



4. Sketch the temperature characteristics of a thermistor.

5. Distinguish between e.m.f. and p.d. in terms of energy considerations. The electromotive force (e.m.f.) of a source is defined using the energy converted from non-electrical to electrical per unit charge driven through the source while potential difference between two points is defined using energy converted from electrical to non- electrical per unit charge passing from one point to the other.

6. What is the effect of internal resistance of a source of e.m.f. on the terminal potential difference and output power? For a given external load, internal resistance will cause the terminal potential difference to be lower than the e.m.f. The output power will also be lower than the power generated by the source.

7. Explain the use of thermistor in potential dividers to provide a potential difference which is dependent on temperature.

Thermistor is sensitive to temperature changes. When temperature increases, its resistance decreases.

Hence, the p.d. across the thermistor decreases, while p.d. V across the resistor R increases.

8. Suggest a practical example of the use of a thermistor. Digital thermometers such as Oral Digital thermometer (ODT). Microwave ovens use thermistors to detect and adjust internal temperature to prevent

overheating. Digital thermostats



9. Explain the use of light dependent resistors (LDR) in potential dividers to provide a potential difference which is dependent on illumination.

Light dependent resistor (LDR) is sensitive to illumination. When illumination increases, resistance decreases.

Hence, the p.d. across LDR decreases, while p.d. V across the resistor R increases.

10. Suggest a practical example of the use of a LDR. Automatic lighting control

e.g. Switch for automatic street lamp / night lamp



Chapter 8: Motion in a Circle

Definitions 1. The radian is the angle subtended by an arc length equal to the radius of the circle.

2. Angular displacement is the angle turned about the centre of the circle.

3. Angular velocity is the rate of change of angular displacement. (units : rad s1) 4. Centripetal force is the resultant force acting on an object in uniform circular motion and is

directed towards the centre of the circle.

Sample Explanation Questions 1. What is meant by uniform circular motion?

Uniform circular motion is the motion of an object moving in circular path at constant speed.

2. Why is there no work done on an object moving in uniform circular motion? There is no work done on the object, as there is no displacement in the direction of the resultant force (resultant force is always perpendicular to the velocity).

3. Explain why there is no change in kinetic energy of the object moving in uniform circular motion even though there is a resultant force acting on it. In uniform circular motion, the resultant force is always perpendicular to the velocity. This changes the direction of motion, but the speed is constant. Hence no change in the kinetic energy of the object.



Chapter 9: Gravitational field

Definitions 1. A gravitational field is a region of space where a mass will experience a gravitational force

when placed in that field.

2. Gravitational field strength at a point is defined as the force per unit mass acting on a small mass placed at that point.

3. Newtons law of gravitation states that the gravitational force of attraction between two point masses is proportional to the product of the masses and inversely proportional to the square of their separation.

4. The gravitational potential at a point is defined as the work done per unit mass (by an external agent) in bringing a small mass from infinity to that point.

5. Gravitational potential energy of an object at a point is defined as the work done (by an external agent) in bringing the object from infinity to that point.

6. Geostationary orbits are orbits of satellites orbiting around the Earth such that these satellites would appear stationary when observed from the Earth.

Sample Explanation Questions 1.

Derive 2=GMgr

.

Newtons law of gravitation : 2GMmF

r=

From the definition of gravitational field strength, 2

2

GMmF GMrg = = =m m r

2. What is meant by geostationary orbits? Geostationary orbits are orbits of satellites orbiting around the Earth such that these satellites would appear stationary when observed from the Earth. Hence, the period of the satellites orbits must be the same as that of the Earth, i.e. 24 hours, and these satellites would also have to orbit about the Earths axis of rotation, i.e. from West to East directly above the Equator.

3. Explain why a geostationary satellite must be above the equator. The gravitational force by the Earth on the satellite is directed towards the centre of Earth. The centripetal force is directed towards the centre of its orbit. For any satellite, the centre of the orbit must be the centre of the Earth. In order for the satellite to appear stationary when observed from the Earth, the axis of rotation of the satellite must be the same as the axis of rotation of the Earth. Hence geostationary satellite must be above the equator.



4. What are the analogies between gravitational and electric fields? Analogy G-Field E-Field

Origin of force mass m charge Q

Fundamental law 2MmF = -Gr

21

4 oQqFrpi

=

Field strength

Force per unit mass.

g = gravitational forcemass

Force per unit positive charge.

E = electric forcepositive charge

Field strength of isolated point mass or charge

2GMgr

= 21

4 oQErpi

=

Uniform field Near surface of the Earth Between parallel plate:

VEd

=

Potential at a point Wm

= WV q=

Change in potential energy, U = U m = U q V

Relationship

dUFdr

=

dgdr

=

dUFdr

=

dVEdr

=

5 Explain why gravitational potential is always negative. Potential at infinity is taken to be zero. Due to the attractive nature of the gravitational force, work done by an external agent to bring any mass from infinity to that point is always negative. Hence the potential at any point must always be negative.



Chapter 10: Oscillations

Definitions 1. Simple harmonic motion of an object is a periodic motion where its acceleration is

proportional and opposite to its displacement from the equilibrium position. 2. Amplitude is the maximum distance moved by an object from the equilibrium position. 3. Period is the time taken for one complete oscillation. 4. Frequency is the number of complete oscillations per unit time. 5. Angular frequency is the product of 2pi radian and the frequency. 6. Phase difference is the difference in the stages of motion between two oscillations at a

specific time. 7. Damped oscillation of a system is one that is decreasing in amplitude with time due to

dissipative forces acting on the system.

Sample Explanation Questions 1. State two practical examples of free oscillations.

A simple pendulum oscillating. A mass oscillating at the free end of a helical spring.

2. Describe the interchange between kinetic and potential energies during SHM. EK is maximum at equilibrium position EP is maximum at the extreme positions Total energy is conserved (constant) at all points.

3. Describe practical examples of damped oscillations with particular reference to the effects of the degree of damping. Practical examples: (i) Oscillations of a simple pendulum in air. (ii) Oscillations of a mass attached to a spring immersed in a fluid.

Types of damping: Light damping - system will oscillate with decreasing amplitude. Critical damping - system will return to the equilibrium position in the shortest possible

time without oscillating. Heavy damping - system will take a longer time to return to the equilibrium position

without oscillating.

E / J

x / m + x0 - x0

2202

1.. mxET =

)(.. 220221 xxmEK =

2221

.. xmEP =

2202

1 mx



4. What is meant by resonance?

Resonance is a phenomenon in which a forced oscillating system oscillates with maximum amplitude when the external driving frequency is equal to the natural frequency, f0, of the system.

There is a maximum transfer of energy from the driving system to the driven system.

5. Describe the importance of critical damping in cases such as a car suspension system. The suspension system of a car is designed so that it experiences critical damping. Critical damping allows the car to return to its equilibrium position quickly after it passes an uneven surface.

6. Describe 3 practical examples of forced oscillations and resonance.

Example 1: Microwave oven microwaves will cause the water molecules in the food to vibrate. If the frequency of the microwave is the same as the natural frequency of the water molecules, resonance occurs and the water molecules will vibrate with maximum amplitude, hence heating up the food.

Example 2: Breaking of a glass by a singer sound waves from the singer will cause the glass molecules in the glass to vibrate. If the frequency of the sound wave is the same as the natural frequency of the glass goblet, resonance occurs and the glass structure will vibrate with maximum amplitude, hence may crack the glass.

Example 3: A note produced by a musical instrument. E.g. plucking of a guitar string produces a dominant sound/note whose frequency is the same as the natural frequency of the vibrating string. The natural frequency of the string is dependent on its tension and effective length.

Amplitude

Frequency f0



7. Describe graphically how the amplitude of a forced oscillation changes with frequency and damping near to the natural frequency, f0, of the system.

Amplitude of oscillation increases when frequency of forced oscillations is near to the natural frequency of the oscillating system. The higher the damping, the lower the amplitude.

8. Why should resonance be avoided in some cases and how can it be done? Resonance will produce maximum amplitude of oscillation which may cause disintegration of the oscillating system. Resonance can be avoided by adjusting the natural frequency of the oscillating system to be far from the driving frequency.

Driving frequency

Amplitude

f0

Light damping

Lighter damping



Chapter 11: Wave Motion

Definitions 1. Displacement of a particle is its distance in a given direction from its equilibrium position. 2. Amplitude is the magnitude of the maximum displacement of a particle from its equilibrium

position. 3. Phase difference between two points in a wave is the difference between the stages of

oscillations, expressed in terms of an angle. (e.g. Two points half a wavelength apart has a phase difference of pi radians)

4. Period is the time taken for an element of the wave to complete one oscillation. 5. Frequency of a wave is the number of oscillations per unit time made by an element of the

wave.

6. Wavelength of a wave is the shortest distance between two points which are in phase. 7. The speed of a wave is the distance travelled by the wave per unit time. 8. Intensity of a wave is the rate of incidence of energy per unit area normal to the direction

of propagation of the wave.

Sample Explanation Questions 1. What is meant by a wave?

A wave is a mechanism for the transfer of energy from one point to another without the physical transfer of any material between the points.

2. Deduce the equation v f = The wavelength is the distance travelled by the wave in one period.

Hence, speed of the wave motion, v = dis tance travelled by the wavetime taken

=

T

= 1f

= f

3. Distinguish between Transverse and Longitudinal waves. Transverse waves Longitudinal waves

Transverse waves are waves in which the direction of oscillation is PERPENDICULAR to the direction of wave motion.

Longitudinal waves are waves in which the direction of oscillation is PARALLEL to the direction of wave motion.

Can be polarized. Cannot be polarized.

4. What do you understand by polarization? It is a phenomenon in a transverse wave where the oscillation of the elements of the wave is restricted to a plane.



Chapter 12: Superposition

Definitions 1. Interference is the superposing of two or more waves to give a resultant wave whose

amplitude is given by the Principle of Superposition. 2. The Principle of Superposition states that the resultant displacement at a point due to two

or more waves is the vector sum of the displacements due to those waves acting individually.

3. Diffraction is the spreading of waves through an aperture or round an obstacle. It is observable when the width of the aperture is of the same order of magnitude as the wavelength of the waves.

4. Sources are said to be coherent if they have a constant phase difference.

Sample Explanation Questions 1. What are the conditions to form stationary waves?

two progressive waves of same type, moving in opposite direction superimpose with each other. for transverse waves, the waves must be unpolarized, or polarized in the same plane similar frequency & wavelength (waves are NOT coherent) similar amplitude

2. What are the conditions required for observable interference? Interfering waves must be

same type, coherent, have approximately the same amplitude, for transverse waves, the waves must be unpolarized or polarized in the same plane.

3. Distinguish between progressive and stationary waves? Criteria Progressive Stationary

Energy is propagated. is not propagated. Waveform advances does not advance. Amplitude All wave elements have the same

amplitude. All wave elements between a node and adjacent antinode have different amplitudes.

Wavelength The wavelength is the shortest distance between two points which are in phase.

The wavelength is twice the distance between adjacent nodes or antinodes.

Phase All wave elements within a wavelength have different phase.

All wave elements between two adjacent nodes are in-phase.



Chapter 13: Electric Fields

Definitions 1. An electric field is a region of space where a charge will experience an electric force when

placed in that field 2. Electric field strength at a point is defined as the electric force per unit positive charge

placed at that point. 3. Coulombs Law states that the force between two point charges is directly proportional to

the product of the charges and inversely proportional to the square of their separation. 4. Electric potential at a point is defined as the work done per unit charge (by an external

agent) in bringing a small positive charge from infinity to that point.

Sample Explanation Questions 1 Describe the effect of a uniform electric field on the motion of charged particles.

i) If the charged particle is not moving parallel to the electric field, the charges will move in a parabolic path.

ii) If the charged particle is moving parallel to the electric field, the acceleration will also be parallel to the field. Hence, the motion will be along the same straight line.

2. Distinguish qualitative and quantitative aspects of electric field and gravitational field.

Electric field Gravitational field Similarities

Both are inverse square law fields (i.e. r

21 )

Both do not require a medium to exert their influence.

Differences

Acts on charges Acts on masses

Electric forces can be attractive or repulsive

Gravitational forces are always attractive

Field lines are always directed away from positive point charge towards negative point charge.

Field lines are always directed towards point masses.



Chapter 14: Electromagnetism Definitions 1. A magnetic field is a region of space where a force acts on an electric current in a wire,

moving charge or a permanent magnet. 2. Magnetic flux density is defined as the force per unit length of conductor per unit current

placed perpendicular to the magnetic field. 3. The tesla is the magnetic flux density of a magnetic field if the force of 1 N is acting on 1 m

length of conductor carrying a current of 1 A placed perpendicular to the field. Sample Explanation Questions 1. Describe and analyse deflections of beams of charged particles by uniform electric

and uniform magnetic fields. Beams of charged particles moving perpendicular to a uniform electric field are deflected along parabolic paths. Beams of charged particles moving perpendicular to a uniform magnetic field are deflected in circular paths. (The direction of the centripetal force is given by Flemings left hand rule).

2. Explain how electric and magnetic fields can be used as velocity selection for charged particles. Crossed uniform magnetic and electric fields (i.e. both fields are perpendicular to each other) which produce forces opposite in directions on charged particles could be used to select particles of a particular speed.

As shown above, the moving charged particle will experience opposing forces. The charged particles will remain on a straight path if the magnitude of electric force FE and the magnetic force FB are equal, i.e. FB = FE qvB = qE

Hence, v = EB

By changing the ratio of E to B, we will be able to select particles of a certain velocity.

3. Explain why there are forces between current-carrying conductors and predict the direction of the forces Each current carrying conductor will induce a magnetic field around itself (the direction of the magnetic field induced is predicted by the right-hand grip rule). This magnetic field will interact with the current flowing in the other conductor, resulting in an attractive or repulsive force on the conductor. The direction of the force acting on each conductor is predicted by Flemings left-hand-rule.

4. Explain how the magnetic flux density of a coil or solenoid may be increased. 1. increasing the current in the coil or solenoid 2. inserting a soft ferrous (iron) core in the coil or solenoid.

.



Chapter 15: Electromagnetic Induction

Definitions 1. Magnetic flux through an area is the product of that area and the component of the flux

density directed normal to the plane of that area. 2. The weber (Wb) is the magnetic flux through an area of 1 m2 if the flux density normal to

the plane of that area is 1 T. 3. Magnetic flux linkage through a coil is the product of magnetic flux and the number of

turns of the coil. 4. Faradays law states that the magnitude of induced e.m.f. in a coil is proportional to the rate

of change of magnetic flux linkage through that coil. 5. Lenzs law states that the direction of the induced current is such that its effect opposes the

change producing it.

Sample Explanation Questions 1. Explain simple applications of electromagnetic induction.

(i)Turbine generator The coil of the turbine is positioned in strong magnetic field. Turbine uses force to turn its coil. Hence, coil experiences changing magnetic flux linkage. According to Faradays law, e.m.f. is induced.

(ii) Electric guitar pick up Vibrating string induces an e.m.f. in a coil. The pickup coil is placed near the vibrating guitar string, which is made of a metal

that can be magnetized. The permanent magnet inside the coil magnetizes the portion of the string nearest

the coil. When the guitar string vibrates at some frequency, its magnetized segment

produces a changing magnetic flux through the pickup coil. The changing flux linkage induces e.m.f. in the coil. Subsequently the e.m.f. is fed to the amplifier and speaker system to produce

sound.



Chapter 16: Alternating Currents

Definitions 1. Peak value of an alternating current is defined as the maximum possible value of the

alternating current 2. Root mean square current from an AC source is the current which will produce the same

heating effect in a resistive load as the steady current from a DC source. 3. Rectification is a process of converting an alternating current to a direct current (flowing in

one direction)

Sample Explanation Questions 1. What is a diode?

A diode is an electrical device with two terminals that allows current to flow through it in one direction only.

2. Explain the use of a single diode for the half wave rectification of an alternating current. Diode allows current to flow when forward biased, and disallow current to flow when reversed biased.

Current which flows in one direction is called rectified current.

Hence, when an AC supply is connected in a circuit that consists of a single diode and a resistor in series, only the rectified current can flow through the resistor.

VAB

VXY

t

t

1

1

2

output voltage R

X

Y

A

B

a.c. source



Chapter 17: Quantum Physics

Definitions 1. Photon is a quantum of electromagnetic radiation. 2. Photoelectric effect is a phenomenon where electrons are liberated from the surface of a

metal when the metallic surface is irradiated with electromagnetic radiation of high enough frequency.

3. Threshold frequency of a metal is the frequency of the incident electromagnetic radiation below which no electrons can be liberated from the metal surface.

4. Work function energy of a metal is the minimum energy required to liberate an electron from the surface of the metal.

5. A potential barrier is a region within which the potential energy of the particle is much higher than if the particle were to be outside the barrier.

6. Quantum tunneling is a phenomenon where a particle can appear outside a potential barrier, even though the total energy of the particle is lower than the barrier energy (barrier height).

Sample Explanation Questions 1. Show an understanding that photoelectric effect provides evidence for a particulate

nature of electromagnetic radiation.

The photoelectric experiment displayed the following 4 observations: Result 1: Current is proportional to intensity. This result can be explained using wave nature and particulate nature of light.

Result 2: For every material of cathode irradiated, there is a limiting frequency fo or threshold frequency, below which no electrons would be emitted from the cathode regardless of the light intensity. This result can be explained using particulate nature of light only.

Result 3: The maximum kinetic energy of emitted photoelectrons depends only on the frequency of the incident radiation, and not its intensity. This result can be explained using particulate nature of light only.

Result 4: The emission of photoelectrons starts with no observable time lag, even for very low intensity of incident radiation. This result can be explained using particulate nature of light only.

Hence, photoelectric effect provides the evidence for the particulate nature of electromagnetic radiation.

2. What evidences show that light has wave and particulate natures? Evidence of Wave Nature Evidence of Particulate Nature

Diffraction and interference of light Photoelectric effect



3. Explain photoelectric phenomena in terms of photon energy and work function energy. Using Einsteins photoelectric effect equation:

Photon energy = Work function + Maximum K.E. of electron Work function energy is the minimum energy required to remove an electron from the surface of the metal. If the photon energy is less than the work function energy of the cathode, no photoelectron will be emitted. Hence, to emit photoelectrons, photon energy must be equal or greater than the work function energy of the cathode.

4. Explain the significance of equation 2max

12

hf mv= + . This equation is a statement of principle of conservation of energy. When an electron absorbs energy, hf, from an incident photon, it uses a minimum energy to be emitted from the metal surface, it will have a maximum kinetic energy 2max

12

mv .

5. Describe and interpret qualitatively the evidence provided by electron diffraction for the wave nature of particles. When a beam of electrons passed through a thin film of crystal (e.g. graphite), the dispersion pattern of the emergent electrons produced on a screen (coated fluorescent) is observed to be similar to the diffraction pattern produced by a beam of X-ray. This interference pattern provides evidence for the wave nature of particles like electrons.

6. Distinguish between emission and absorption line spectra.

Emission Line Spectra Absorption Line Spectra

Pattern

Initial state of gas atoms

produced by hot (gas atoms are initially at excited state) vapour or gas.

produced when white light passes through cool (gas atoms are initially at ground state) vapour or gas.

Spectrum Pattern

a series of separate bright lines of definite wavelength on a dark background

a series of separate dark lines of definite wavelength on a coloured background

Distinguishing between

In terms of



Explanation Excited atoms emit photons with the characteristic wavelengths corresponding to the transitions from higher to lower energy levels.

Wavelengths corresponding to bright lines on the spectrum are characteristics of the element emitting the light.

Cool gas absorbs photons with the characteristic wavelengths corresponding to the transitions from lower to higher energy levels.

Subsequently, the excited atoms transit back to the lower energy levels by emitting the same photons in all directions small fraction of emitted photons incident on screen lines of lower intensity formed (appear as dark lines on the spectrum)

Wavelengths corresponding to dark lines on the spectrum are characteristics of the element absorbing and re-emitting the light.

7. Explain how emission spectral lines show discrete energy levels in an atom. An emission spectrum consists of a set of discrete lines of different wavelengths. A photon is emitted from an isolated atom when one of its electrons transits from a

higher to a lower energy level. Energy of the photon is equal to the energy difference between the two levels involved in

the transition. Since the energies of the photons are discrete, this means that the electrons must have transitions between discrete energy levels within the atom.

8. Explain how absorption spectral lines show discrete energy levels in an atom. An absorption spectrum consists of a set of discrete dark lines of different wavelengths

on a coloured background. Only photons of specific wavelengths are absorbed which corresponds to specific energy

transitions in an isolated atom. This atom transitions from lower to higher energy level, and then quickly transitions down by giving out a photon corresponding to the energy transition.

Energies of the photons emitted and absorbed are discrete and hence proves that there are discrete energy levels in an atom.

9. Explain the origins of the features of a typical Xray spectrum using quantum theory. a) The 2 spikes (K and K, line spectrum) is the result of electron transitions within the

atoms of the target material. The electrons which bombard the target are very energetic (approximately 105 eV ) and are capable of knocking electrons out of deep-lying energy levels of the target atoms. An outer electron may fall into the vacancy created in its atom, releasing a high energy quantum of electromagnetic radiation (i.e. X-ray). Since the energy levels are characteristic of the target atoms, so too are the X-rays produced this way. These values of wavelengths are characteristic of the target metal.

b) There is also a continuous spectrum in the background of the 2 spikes. This continuous background is produced by electrons colliding with the target and being decelerated. The energy of the emitted X-ray quantum is equal to the energy lost in the deceleration. An electron may lose any fraction of its energy in this process.

c) The most energetic X-rays (those with min) are the result of bombarding electrons losing all their energy at once. Since the energy of the electrons depends on the operating voltage, so does

min. X-rays with longer wavelength are the result of electrons losing less than their total energy.



10. Explain qualitatively the phenomenon of quantum tunnelling of an electron across a potential barrier. Electron is considered as a wave function. Probability of finding an electron is directly proportional to the square of the amplitude

of its wave function. When the wave function of an electron encounters a potential barrier, its amplitude

decreases exponentially. For a narrow barrier, the wave amplitude may not become zero after the electron passes

through the barrier. Hence, there is a non-zero probability that the electron will be found beyond the barrier. This process is called quantum tunnelling.

11. Describe the application of quantum tunnelling to the probing tip of a scanning tunnelling microscope (STM). The probing tip of an STM is positioned at a very small distance above the conducting

sample surface which represents the width of the potential barrier. Electrons can cross the potential barrier between the tip and the surface through the

process of quantum tunnelling. A small potential difference is applied between the tip and the surface to produce

tunneling current. The tunnelling current I decreases exponentially with the tip-surface distance d, so a

small change in d will induce a large change in I. This variation will allow the mapping of atomicscale images of a surface.



Chapter 18: Lasers and Semiconductors

Definitions 1. Spontaneous emission is the emission of a photon due to a transition of electron from a

higher to a lower energy level without external stimulation. 2. Stimulated emission is the emission of a photon due to a transition of electron from a

higher to a lower energy level when stimulated by an incoming photon of the same frequency.

3. Population inversion is a condition when most of the atoms are in the excited state. 4. Band gap refers to the energy difference between two allowed energy bands OR the

minimum energy needed for an electron to jump from the lower band to the higher band. 5. Depletion region at a p-n junction is a region virtually depleted of mobile charge carriers

due to the recombination of electrons and holes at a finite temperature.

Sample Explanation Questions 1. Explain the action of a laser in terms of population inversion and stimulated

emission. Pumping creates a state of population inversion. Spontaneous emission occurs and photons are emitted. Photons travel and interact with excited atoms causing stimulated emission. Photons in the laser cavity cause further stimulated emission. Since all these stimulated photons are parallel and coherent, they form a laser beam

which is monochromatic, coherent and highly directional.

2. Describe the formation of energy bands in a solid. A solid contains a very large number of atoms closely packed together. Hence, the allowed energy level split into a very large number of levels known as energy band for many atoms that are very close to one another in a solid.

3. Distinguish between conduction band and valence band. The highest occupied band is called valence band. The lowest unoccupied band is called conduction band.

4. Why metal is a better electrical conductor than an insulator? Conduction band of a metal is partially filled. Hence, electron is free to move in metal. For insulator, band gap between conduction band and valence band is wide (in the order of few eV). Thermal excitation can only produce an insignificant number of electrons in the conduction band. Hence, it is a poorer conductor.



5. Why a semiconductor is a better electrical conductor than an insulator? For a semiconductor, the band gap between conduction and valence band is narrow (in the order of 1 eV). At finite temperatures, thermal excitation will excite significant number of electrons from valence to conduction band. For insulator, band gap between conduction band and valence band is wide (in the order of few eV). Thermal excitation can only produce an insignificant number of electrons in the conduction band. Hence, it is a poorer conductor than an insulator.

6. Distinguish between an intrinsic and extrinsic semiconductor. An intrinsic semiconductor is a semiconductor without added impurities. An extrinsic semiconductor is a semiconductor with added impurities.

7. Analyse qualitatively how n- and ptype doping change the conduction properties of semiconductors. n-type doping means adding impurity atoms of higher valency. This would provide more mobile electrons to increase the conductivity of the semiconductor.

p- type doping means adding impurity atoms of lower valency. This would provide more holes to increase the conductivity of the semiconductor.

8. Discuss qualitatively the origin of the depletion region at a p-n junction and use this to explain how a p-n junction can act as a rectifier. Diffusion of the electrons occurs from n- to p-type region of a p-n junction. Holes diffuse in the opposite directions. They meet and recombine to form a depletion region consisting of positive and negative immobile ions. An electric field is set up in the depletion region directed from n to p-type (junction electric field).

In forward biased, the external electric field opposes the junction electric field. Hence, the majority charge carriers flow across the junction, resulting in a considerable electric current. In reverse biased, the external electric field reinforces the junction electric field. Hence, only the minority charge carriers flow resulting in negligible electric current flow.



Chapter 19: Nuclear Physics

Definitions 1. Isotopes of an element are atoms whose nuclei have the same number of protons but

different number of neutrons. 2. Mass defect of a nucleus is the difference between the total mass of its individual nucleons

and the mass of the nucleus. 3. Binding energy of a nucleus is the minimum energy required to break the nucleus into its

individual nucleons. 4. Activity of a sample is the number of radioactive decay per unit time. 5. Decay constant is the fraction of the radioactive nuclei in a sample of the nuclide that has

decayed per unit time. 6. Half-life of a radioactive nuclide is defined as the time taken for half of the original number of

radioactive nuclei in a sample to decay. 7. Nuclear fission is the breaking up of a large nucleus into two or more smaller nuclei, with

the emission of a few neutrons and/or other radiations 8. Nuclear fusion is the formation of a larger nucleus from two small nuclei, with the possible

emission of other radiations.

Sample Explanation Questions 1. Infer from the results of the -particle scattering experiment the existence and small

size of the nucleus. Some alpha particles are deflected at large angles indicating that there are massive particles in the gold foil. Most of the alpha particles are undeflected indicating that this massive particle are small in size.

2. Distinguish between nucleon number and proton number. Nucleon number is the total number of protons and neutrons in a nucleus. Proton number of a nucleus is the number of protons in it.

3. How is the binding energy of a nucleus related to its mass defect? Using E = mc2, Binding energy is the energy equivalence of its mass defect.



4. Sketch the variation of binding energy per nucleon with nucleon number.

5. Explain the relevance of binding energy per nucleon to nuclear fission and fusion. The higher the binding energy per nucleon of a nuclei, the more stable the nuclei is due

to a lower energy content. In nuclear fission or fusion, the products have higher binding energy per nucleon than the

reactants. Hence, they are more stable than the reactants. Therefore, these processes release energies.

The End

ALL THE BEST FOR YOURE A-LEVEL EXAMINATION!!

5626Fe

H2 Physics (9646) A-level Physics Formula List

cfs201002@jj / kpl2012 Page 1 of 4

Formula List for Physics (9646)

Syllabus

Reference Use Recall & Use

Derive, Recall

& Use 1 MEASUREMENT (h)

If C = A B

C = A + B

If E = AB or E = A

B

E A B

E A B

2 KINEMATICS (d) v =

s

t

(e) a =

v

t

(f)

v = u + at

s = ut + 12

at2

v2 = u

2 + 2as

3 DYNAMICS (d)

p = mv, I = Ft p : momentum, I : impulse

(e) F =

p

t

(f) F = ma

(i) Relative speed of approach = relative speed of separation

u1 u2 = v2 v1

4 FORCES (a) Spring force, F = kx

(b)

U = 12

Fx = 12

kx2

U : Elastic PE

(d) p = gh

(m)

= Fd : Torque

5 WORK, ENERGY

and POWER (a) W = Fs

(b) W = pV

(d) Ek =12

mv2

(g) F =

pE

x

(h) Ep = mgh

(j) Efficiency, =

out

in

W

W

(k) P =

W

t P = Fv

6 MOTION in a

CIRCLE

(a) s : arc length r : radius

: angle in radians s = r

(b) : angular velocity

=t

(c) v : linear velocity v = r

(e) a : linear acceleration

a = r2, a =

2v

r

(f) F = mr

2, F =

2mv

r



Syllabus

Reference Use Recall & Use

Derive, Recall

& Use 7 GRAVITATIONAL

FIELD

(a) g : gravitational field strength

g =F

m

(b) F : gravitational force

F = G 1 22

m m

r

(c) g =

2

GM

r

(g) =

GM

r

: gravitational potential

(i) Orbit of satellites

2

GMm

r=mr

22

T

8 OSCILLATIONS (c) T =

1

f, T =

2

(d) a = 2x

(e) x = xo sin t

(f) v = vo cos t,

v = 2 2( )ox x

9 THERMAL

PHYSICS

(f) T/K = T/C + 273.15

(g) Q = mcT

(h) Q = mL

(j) U = Q + W

(k) pV = nRT

(n) E = 32

kT 21

2m c = 3

2kT

10 WAVE MOTION (b) v = f (e) intensity (amplitude)

2

11 SUPERPOSITION (c)

Stationary waves NN = AA =

2

NN : node to node AA : antinode to antinode

(i) Double slit interference

=ax

D

(j) Diffraction d sin = n

12 ELECTRIC FIELDS (a) E : electric field strength

E =F

q

(c) F : electric force F =

1 2

24 o

Q Q

r

(d) E = 24 o

Q

r

(e) V : potential difference

E =V

d

(f) F = qE = q

V

d

(h) V =

W

q



Syllabus

Reference

Use Recall & Use Derive, Recall

& Use (i)

E = potential gradient

= V

d

(j) =

4 o

Q

r

: electric potential

13 CURRENT of

ELECTRICITY

(c) Q = It

(e) V =

W

Q

(f) P = VI = I

2R =

2V

R

(h) V = IR

(k) R =

A

(l) E =

W

Q

14 D.C. CIRCUITS (c) R = R1 + R2 + .... Resistance in series

(d)

1 2

1 1 1

R R R + Resistance in parallel

(f)

1 1

2 2

V R

V R

15 ELECTRO-

MAGNETISM

(b) F : magnetic force B : magnetic flux density l : current

F = BI sin

(f) F = BQv sin

(g) qE = ma, BQv =

2mv

r

(h) Velocity selector v =

E

B

(k) B =

2

oI

d

1 2

2

oI IF

d

16 ELECTRO-

MAGNETIC

INDUCTION

(b) : magnetic flux = BA

(c) : magnetic flux linkage

= N = NBA

(e) E : induced emf E =

t

17 ALTERNATING

CURRENTS

(b) =

2

oP

(c) x = xo sin t

(d) Irms =

2

oI

(e)

ps s

p p s

IN V

N V I



Syllabus

Reference

Use Recall & Use Derive, Recall

& Use 18 QUANTUM

PHYSICS

(b) E = hf

(e) 21max2

mv = eVs

(h) : work function hf = + 21max2

mv

(j) de Broglie wavelength =

h

p

(m) hf = E1 E2

(o) Heisenberg uncertainty principles

(x)(px) 4

h

,

(t)(E) 4

h

(s) T exp(2kd) T : transmission coefficient

(t) R : reflection coefficient

R + T = 1

20 NUCLEAR

PHYSICS

(f) E = mc2

(o) A : activity : decay constant N : number of undecayed nuclei

A = N

(p) x = xo exp(-t)

(r) =

12

0.693

t

9646 H2 PHYSICS (2013)

31

DATA AND FORMULAE Data

speed of light in free space c = 3.00 108 m s1

permeability of free space 0 = 4 107

H m1

permittivity of free space 0 = 8.85 1012

F m1

(1/(36)) 109 F m1

elementary charge e = 1.60 1019 C

the Planck constant h = 6.63 1034 Js

unified atomic mass constant u = 1.66 1027 kg

rest mass of electron me = 9.11 1031

kg

rest mass of proton mp = 1.67 1027

kg

molar gas constant R = 8.31 J K1

mol1

the Avogadro constant NA = 6.02 1023

mol1

the Boltzmann constant k = 1.38 1023 J K1

gravitational constant G = 6.67 1011 N m2 kg2

acceleration of free fall g = 9.81 m s2

Formulae

uniformly accelerated motion s = ut + 2

1 at2

v2

= u2 + 2as

work done on/by a gas W = pV

hydrostatic pressure p = gh

gravitational potential = Gm/r

displacement of particle in s.h.m. x = x0sin t

velocity of particle in s.h.m. v = v0cos t

= )(

22

0 xx

mean kinetic energy of a molecule of an ideal gas E = 2

3 kT

resistors in series R = R1 + R2 + ....

resistors in parallel 1/R = 1/R1 + 1/R2 + ....

electric potential V =

r

Q

04

alternating current/voltage x = x0 sin t

transmission coefficient T

where k

=

exp(2kd)

2

2)(8

h

EUm

radioactive decay x = x0 exp(t)

decay constant =

2

1

0.693

t

9646 H2 PHYSICS (2013)

4

SCHEME OF ASSESSMENT All school candidates are required to enter for Papers 1, 2, 3 and 4. All private candidates are required to enter for Papers 1, 2, 3 and 5.

Paper Type of Paper Duration Weighting (%) Marks

1 Multiple Choice 1 h 15 min 20 40

2 Structured Questions

Planning 1 h 45 min

25

5

60

12

3 Longer Structured Questions 2 h 35 80

4 School-based Science Practical Assessment (SPA)

- 15 40

5 Practical Paper 1 h 50 min 15 36

Paper 1 (1 h 15 min, 40 marks)

40 multiple-choice questions. All questions will be of the direct choice type with 4 options. Paper 2 (1 h 45 min, 72 marks)

This paper will consist of a variable number of structured questions plus one or two data-based questions, and a question on Planning. All questions are compulsory and answers will be written in spaces provided on the Question Paper. The data-based question(s) will constitute 1520 marks whilst the Planning question constitutes 12 marks for this paper. The Planning Question will assess appropriate aspects of objectives C1 to C5 and may require candidates to integrate knowledge and understanding from different areas of the syllabus. Paper 3 (2 h, 80 marks)

This paper will consist of: section A worth 40 marks consisting of a variable number of structured questions, all compulsory.

These include questions which require candidates to integrate knowledge and understanding from different areas of the syllabus;

section B worth 40 marks consisting of a choice of two from three 20-mark questions. All answers will be written in spaces provided on the Question Paper. Paper 4 (40 marks)

The School-Based Science Practical Assessment (SPA) will take place over an appropriate period that the candidates are offering the subject. There are two compulsory assessments which will assess appropriate aspects of objectives C1 to C5 in the following skill areas: Manipulation, measurement and observation (MMO) Presentation of data and observations (PDO) Analysis, conclusions and evaluation (ACE) Each assessment assesses these three skill areas MMO, PDO and ACE, which may not be necessarily equally weighted, to a total of 20 marks. The range of marks for the three skill areas are as follows: MMO, 48 marks; PDO, 48; ACE, 810 marks.

9646 H2 PHYSICS (2013)

25

MATHEMATICAL REQUIREMENTS

Arithmetic

Candidates should be able to:

(a) recognise and use expressions in decimal and standard form (scientific) notation. (b) use appropriate calculating aids (electronic calculator or tables) for addition, subtraction,

multiplication and division. Find arithmetic means, powers (including reciprocals and square roots), sines, cosines, tangents (and the inverse functions), exponentials and logarithms (lg and ln).

(c) take account of accuracy in numerical work and handle calculations so that significant figures

are neither lost unnecessarily nor carried beyond what is justified.

(d) make approximate evaluations of numerical expressions (e.g. 2 = 10) and use such approximations to check the magnitude of machine calculations.

Algebra


(a) change the subject of an equation. Most relevant equations involve only the simpler operations but may include positive and negative indices and square roots.

(b) solve simple algebraic equations. Most relevant equations are linear but some may involve

inverse and inverse square relationships. Linear simultaneous equations and the use of the formula to obtain the solutions of quadratic equations are included.

(c) substitute physical quantities into physical equations using consistent units and check the

dimensional consistency of such equations. (d) formulate simple algebraic equations as mathematical models of physical situations, and

identify inadequacies of such models. (e) recognise and use the logarithmic forms of expressions like ab, a/b, x

n, e

kx; understand the

use of logarithms in relation to quantities with values that range over several orders of magnitude.

(f) manipulate and solve equations involving logarithmic and exponential functions. (g) express small changes or errors as percentages and vice versa.

(h) comprehend and use the symbols , Y, [, , , , /, , ( = x ), , x, x, .

Geometry and trigonometry


(a) calculate areas of right-angled and isosceles triangles, circumference and area of circles, areas and volumes of rectangular blocks, cylinders and spheres.

(b) use Pythagoras theorem, similarity of triangles, the angle sum of a triangle. (c) use sines, cosines and tangents (especially for 0, 30, 45, 60, 90). Use the trigonometric

relationships for triangles:

Abccba

C

c

B

b

A

a cos 2 ;

sin sin sin

222+===

9646 H2 PHYSICS (2013)

26

(d) use sin tan and cos 1 for small ; sin2 + cos2 = 1. (e) understand the relationship between degrees and radians (defined as arc/radius), translate

from one to the other and use the appropriate system in context. Vectors Candidates should be able to: (a) find the resultant of two coplanar vectors, recognising situations where vector addition is

appropriate. (b) obtain expressions for components of a vector in perpendicular directions, recognising

situations where vector resolution is appropriate. Graphs Candidates should be able to: (a) translate information between graphical, numerical, algebraic and verbal forms. (b) select appropriate variables and scales for graph plotting. (c) for linear graphs, determine the slope, intercept and intersection. (d) choose, by inspection, a straight line which will serve as the line of best fit through a set of

data points presented graphically. (e) recall standard linear form y = mx + c and rearrange relationships into linear form where

appropriate. (f) sketch and recognise the forms of plots of common simple expressions like 1/x, x

2, 1/x

2, sin x,

cos x, ex

. (g) use logarithmic plots to test exponential and power law variations. (h) understand, draw and use the slope of a tangent to a curve as a means to obtain the gradient,

and use notation in the form dy/dx for a rate of change. (i) understand and use the area below a curve where the area has physical significance. Any calculator used must be on the Singapore Examinations and Assessment Board list of approved calculators.

9646 H2 PHYSICS (2013)

27

GLOSSARY OF TERMS USED IN PHYSICS PAPERS It is hoped that the glossary will prove helpful to candidates as a guide, although it is not exhaustive. The glossary has been deliberately kept brief not only with respect to the number of terms included but also to the descriptions of their meanings. Candidates should appreciate that the meaning of a term must depend in part on its context. They should also note that the number of marks allocated for any part of a question is a guide to the depth of treatment required for the answer. 1. Define (the term(s) ) is intended literally. Only a formal statement or equivalent paraphrase,

such as the defining equation with symbols identified, being required. 2. What is meant by normally implies that a definition should be given, together with some

relevant comment on the significance or context of the term(s) concerned, especially where two or more terms are included in the question. The amount of supplementary comment intended should be interpreted in the light of the indicated mark value.

3. Explain may imply reasoning or some reference to theory, depending on the context. 4. State implies a concise answer with little or no supporting argument, e.g. a numerical answer

that can be obtained by inspection. 5. List requires a number of points with no elaboration. Where a given number of points is

specified, this should not be exceeded. 6. Describe requires candidates to state in words (using diagrams where appropriate) the main

points of the topic. It is often used with reference either to particular phenomena or to particular experiments. In the former instance, the term usually implies that the answer should include reference to (visual) observations associated with the phenomena. The amount of description intended should be interpreted in the light of the indicated mark value.

7. Discuss requires candidates to give a critical account of the points involved in the topic. 8. Deduce/Predict implies that candidates are not expected to produce the required answer by

recall but by making a logical connection between other pieces of information. Such information may be wholly given in the question or may depend on answers extracted in an earlier part of the question.

9. Suggest is used in two main contexts. It may either imply that there is no unique answer or

that candidates are expected to apply their general knowledge to a novel situation, one that formally may not be in the syllabus.

10. Calculate is used when a numerical answer is required. In general, working should be shown. 11. Measure implies that the quantity concerned can be directly obtained from a suitable

measuring instrument, e.g. length, using a rule, or angle, using a protractor. 12. Determine often implies that the quantity concerned cannot be measured directly but is

obtained by calculation, substituting measured or known values of other quantities into a standard formula, e.g. the Young modulus, relative molecular mass.

13. Show is used when an algebraic deduction has to be made to prove a given equation. It is

important that the terms being used by candidates are stated explicitly. 14. Estimate implies a reasoned order of magnitude statement or calculation of the quantity

concerned. Candidates should make such simplifying assumptions as may be necessary about points of principle and about the values of quantities not otherwise included in the question.

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15. Sketch, when applied to graph work, implies that the shape and/or position of the curve need only be qualitatively correct. However, candidates should be aware that, depending on the context, some quantitative aspects may be looked for, e.g. passing through the origin, having an intercept, asymptote or discontinuity at a particular value. On a sketch graph it is essential that candidates clearly indicate what is being plotted on each axis.

16. Sketch, when applied to diagrams, implies that a simple, freehand drawing is acceptable:

nevertheless, care should be taken over proportions and the clear exposition of important details.

17. Compare requires candidates to provide both similarities and differences between things or

concepts.

TEXTBOOKS Teachers may find reference to the following books helpful. Practice in Physics (3

rd Edition), by Akrill et al, published by Hodder & Stoughton,

ISBN 0-340-75813-9

New Understanding Physics for Advanced Level (4th Edition), by J. Breithaupt, published by Nelson Thornes, ISBN 0-748-74314-6

Advanced Physics (4th Edition), by T. Duncan, published by John Murray, ISBN 0-719-57669-5

Advanced Physics (2nd Edition), by K. Gibbs, published by Cambridge University Press, ISBN 0-521-56701-7

Bath Advanced Science: Physics (2nd Edition), by R. Hutchings, published by Nelson Thornes, ISBN 0-174-38731-8

Physics for Scientists and Engineers with Modern Physics (5th Edition), by R. Serway, published by Saunders, ISBN 0-030-20974-9

Fundamental of Physics (Extended 6th Edition), by R. Resnick, D. Halliday & J. Walker, published by Wiley, ISBN 0-471-22863-X

Physics: Principles with Applications (5th Edition), by D.C. Giancoli, published by Prentice Hall, ISBN 0-13611-971-9 Teachers are encouraged to choose texts for class use that they feel will be of interest to their students and will support their own teaching style.

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SUMMARY OF KEY QUANTITIES, SYMBOLS AND UNITS The following list illustrates the symbols and units that will be used in question papers.

Quantity Usual symbols Usual unit

Base Quantities mass m kg length l m

time t s electric current I A

thermodynamic temperature T K amount of substance n mol Other Quantities distance d m displacement s, x m area A m

2

volume V, v m3

density kg m3

speed u, v, w, c m s1

velocity u, v, w, c m s

1

acceleration a m s2

acceleration of free fall g m s

2

force F N weight W N momentum p N s work w, W J energy E,U,W J potential energy Ep J kinetic energy Ek J heating Q J change of internal energy U J

power P W pressure p Pa torque T N m gravitational constant G N kg

2 m

2

gravitational field strength g N kg1

gravitational potential J kg

1

angle , rad angular displacement , rad angular speed rad s

1

angular velocity rad s1

period T s frequency f Hz angular frequency rad s

1

wavelength m

speed of electromagnetic waves c m s1

electric charge Q C elementary charge e C electric potential V V electric potential difference V V electromotive force E V resistance R resistivity m electric field strength E N C

1, V m

1

permittivity of free space 0 F m1

magnetic flux Wb

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Quantity Usual symbols Usual unit

magnetic flux density B T permeability of free space 0 H m

1

force constant k N m1

Celsius temperature C specific heat capacity c J K

1 kg

1

molar gas constant R J K1

mol1

Boltzmann constant k J K

1

Avogadro constant NA mol1

number N, n, m number density (number per unit volume) n m

3

Planck constant h J s work function energy J

activity of radioactive source A Bq decay constant s

1

half-life t1/2 s relative atomic mass Ar relative molecular mass Mr atomic mass ma kg, u electron mass me kg, u neutron mass mn kg, u proton mass mp kg, u molar mass M kg proton number Z nucleon number A neutron number N

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Physics Defn Pack_Revision_2012