Grade:- 13 (2016) - June - 2016 1 Physics - I
01) In this equation, if h is the Planck constant, f is frequency and V is velocity, then A, B
respectively denote
(1) force, mass
(2) energy, mass
(3) frequency, energy
(4) work, frequency
(5) force, frequency
02) What is the intensity of heat radiation (in Wm-2) at a point 1m from a point that radiates heat at a
rate of 50W?
(1)
(2)
(3) (4)
(5)
03) The ratio between the amplitudes of two waves is 9:1. What is the ratio between the maximum and
minimum sound intensities caused by the interference of these two waves?
(1) (2) (3) (4) (5)
04) A man watches a stone at the bottom of a water tank from above. If the height of the water column
in the tank is h, at what depth will the stone’s image be? (the refractive index of water is n)
(1) (2) (3)
(4)
(5)
05) The length of an iron rod in a Kundt’s tube is 1m. If the frequency of the standing wave formed here
is 2500Hz, what is the speed of sound in the iron rod?
(1) (2) (3)
(4) (5)
06) The ratio of turns in the coils of a step up transformer is 250:1. This transformer has 90% efficiency.
If the current through the primary coil is 250A, what is the current through the secondary coil?
(1) (2) (3) (4) (5)
07) A ring of charge with radius 0.5m has 0.002π m gap. If the ring carries a charge of +1 C, the electric
field at the center is (
)
(1)
(2)
(3)
(4)
(5)
G.C.E. A/L Examination June - 2016
Conducted by Field Work Centre, Thondaimanaru
In Collaboration with
Zonal Department of Education Jaffna.
Time :- Two hours Grade :- 13 (2016) Physics - I
FWC
Grade:- 13 (2016) - June - 2016 2 Physics - I
08) Which of the following statements about Ultrasound is not true?
(1) It moves with the velocity of sound.
(2) It has a higher frequency than normal sound.
(3) It cannot be heard by human ears.
(4) It has a lower wavelength than normal sound.
(5) It does not cause Doppler Effect.
09) The figure shows a uniform, solid, right circular cone kept in equilibrium with its vertex touching a
horizontal surface. This equilibrium is unstable. Which of the following statements is not suitable to
explain this?
(1) The position of the center of gravity is higher.
(2) The cone is symmetrical about its axis.
(3) The narrow part is kept in contact with the surface.
(4) Its potential energy is at a higher level.
(5) The couple which acts when the cone inclines slightly, will topple it
10) A driller with a power of P W is used to drill a hole in a copper block of mass M kg. The specific heat
capacity of copper is S Jkg-1K-1. 40% of the power is used to heat up the drill. What is the rise in
temperature of the copper block at time T s?
(1)
(2)
(3)
(4)
(5)
11) A sine alternating current with peak value flows through resistor R. What is the rate at which
heat is produced in the resistor R?
(1) (2)
(3) (4)
√ (5)
12)
Four positions of a heavy rod of weight w are shown in the above figures. In which of these figures
is balance possible?
(1) (2) (3) (4) (5)
13) In the circuit shown in the figure, the charges
stored in C1 and C2 respectively are,
(1)
(2)
(3)
(4)
(5)
Rope Rope
Smooth
wall
Smooth
wall
Smooth floor
Fig - Fig - Fig -
Fig -
pivoted
Grade:- 13 (2016) - June - 2016 3 Physics - I
14) What is the single logic gate that is equivalent to the combination of gates given below?
(1) AND gate (2) OR gate (3) XOR gate (4) NAND gate (5)NOR gate
15) Two artificial satellites, A and B, revolve around the Earth.
The mass and the radius of orbit of A are twice that of B.
What is the ratio between the linear velocities
?
(1)
(2)
(3) √
(4)
√
(5)
16) 1 mol of a monatomic ideal gas is taken from A
to B through path ACB. If the temperature at A is
T0, what is the amount of heat absorbed by the
gas during the process ? (for a
monatomic gas,
and
)
(1)
(2)
(3)
(4)
(5)
17) Two balls, A and B are thrown from the same spot at the same time. A is thrown vertically upwards,
while B is thrown with an angle of 30o from the vertical. If the two balls reach the ground at the
same time, what is the ratio between the velocities with which each ball, A, B, is thrown?
(1) √ (2) √ (3) √ (4) √ (5)
18) A ring of radius r and mass m, which is made from a thin wire, is placed horizontally within a liquid
of surface tension T. What is the minimum force required to tale this ring out through the liquid
surface? (the contact angle is zero)
(1) (2) (3)
(4) (5)
B
A
C
Pressure
Volume
Grade:- 13 (2016) - June - 2016 4 Physics - I
19)
The operational amplifier shown in the diagram works with a supply of +15V - -15V. What is the
output voltage, Vout, of the circuit?
(1) (2) (3)
(4) (5)
20) A hemispherical portion has been removed from a solid cylinder of
radius r. the mass and volume of the remaining part of the cylinder
is m and v respectively. As shown in the figure, this cylinder is held
by a string in a liquid of density ρ, with its upper surface at depth h.
What is the force exerted by the liquid on the lower surface of the
cylinder?
(1)
(2)
(3)
(4)
(5)
21) If the wavelength of maximum intensity of the sun’s radiation is 510nm and that of another star is
350nm, what is the ratio between the surface temperatures of the sun and the other star?
(1) (2) (3)
(4) (5)
22) A compound microscope has two converging lenses of focal length 3cm and 5cm. A man with least
distinct vision at 25cm observes an object kept 4cm in front of the objective. The microscope is
adjusted so that the final image is at infinity. What is the separation of the lenses?
(1)
(2)
(3)
(4)
(5)
Grade:- 13 (2016) - June - 2016 5 Physics - I
23)
Sphere A of mass m, moving with velocity V, collides with sphere B of mass nm, travelling in the
same direction with velocity kV. After the collision, if sphere A comes to rest, what is the velocity of
sphere B?
(1) (
) (2) (
) (3) (
)
(4) (
) (5) (
)
24) A cube of side length a, moves with velocity V, along a smooth horizontal
surface, as shown in the figure. It collides with an obstacle at point O. What is
the angular velocity of the block after the collision? (The moment of inertia of
the block about a perpendicular to plane horizontal axis through one of its
vertex is
ma2)
(1)
(2)
(3)
√
√
(4) √
(5)
25) The diagrams show particle movement in an air column when a stationary wave exists in the
column. The first diagram shows the displacement of some particles at one instant and the second
diagram shows the displacement of particles half a cycle later.
What is the length L if the column in terms of the wavelength λ, and at which position within the
column does the pressure change by the largest amount?
Length maximum pressure change at
(1)
node
(2)
antinode
(3)
node
(4)
antinode
(5)
antinode
Grade:- 13 (2016) - June - 2016 6 Physics - I
26) In a helium-neon laser, helium atoms collide with neon atoms and excite them. This produces a
population inversion which allows stimulated emission. Which neon energy level diagram correctly
shows the excitation of the neon atoms by the helium atoms, the spontaneous infra-red emission
from the neon, and the stimulated emission of red light?
27) In a prism shaped network made of nine conductors, each having 5Ω resistance, what is the
equivalent resistance between the point A and B?
(1)
(2)
(3)
(4)
(5)
28) The figure shows a metal ball of volume 400cm3, floating in a
mercury-water interface in a vessel. Half of the ball is immersed in
mercury. What will happen if liquid X, with density 9400kgm-3 is
poured into this vessel? (The density of mercury is 13600 kgm-3 and
that of water is 1000 kgm-3)
(1) The ball will float with 300 cm3 in liquid X and 100 cm3 in mercury.
(2) The ball will float with 300 cm3 in liquid X and 100 cm3 in water.
(3) The ball will float with 100 cm3 in liquid X and 300 cm3 in water.
(4) The ball will float with 200 cm3 in liquid X and 200 cm3 in water.
(5) The ball will float with 200 cm3 in liquid X and 200 cm3 in mercury.
spontaneous emission
stimulated emission
(1) (2)
(3) (4)
(5)
Grade:- 13 (2016) - June - 2016 7 Physics - I
29) In a practical Wheatstone bridge circuit, when one more resistance of 100Ω is connected in parallel
with unknown resistance x, then the ratio of
becomes 2. is the balance length. AB is a uniform
wire. Then the value of x must be
(1) (2) (3) (4) (5)
30) A milli-ammeter of range 10mA and resistance 9Ω is
joined in a circuit as shown in the figure. The meter
gives full scale deflection, when current in the main
circuit is I, and A and D are used as terminals. The value
of I is
(1) (2) (3) (4) (5)
31) Two stones are thrown vertically upwards at the same time with velocities u1, u2 (u2>u1). They reach
the ground in 6s and 10s respectively. Which graph shows the change of difference in
displacement, Δx, of the two stones during the journey with time? Consider that the stones do not
bounce on hitting the ground.
(1) (2) (3) (4) (5)
32) The figure shows a light ray entering normal to a surface of a glass right prism, of which one angle is
60o. the emergent ray is
(1) (2) (3) (4) (5)
Copper strip
Copper strip
Grade:- 13 (2016) - June - 2016 8 Physics - I
33) A bungee jumper has 24kJ of gravitational potential energy at the top of his jump. He is attached to
an elastic rope which starts to stretch after a short time of free fall. The values of gravitational
potential energy, elastic potential energy and kinetic energy are given for the top and bottom of
the jump.
Gravitational potential
energy (kJ)
Elastic potential
energy (kJ)
Kinetic energy (kJ)
Top
Bottom
Which row of the table below shows possible values of these three energies when the jumper is
halfway down? Losses of energy through air resistance are negligible.
Gravitational potential
energy (kJ)
Elastic potential
energy (kJ)
Kinetic energy
(kJ)
(1)
(2)
(3)
(4)
(5)
34) As shown in the figure, a uniform rod has a wooden section and a solid rubber handle. The length of
the handle is and the length of the wooden section is 4 . The rod balances at a distance of 2
from the rubber end. What is the ratio between the densities of rubber and wood?
(1) (2) (3)
(4) (5)
35) The least distance of distinct vision of an old man is 60cm. He can see distant objects clearly. If the
distance between his eye lens and retina is 3cm, what is the least focal length that his eye lens can
achieve?
(1)
(2)
(3)
(4)
(5)
Grade:- 13 (2016) - June - 2016 9 Physics - I
36) A fixed amount of ideal gas has pressure P and volume V. The graph shows the variation of
with V
at a constant temperature. The amount of gas and the thermodynamic temperature are both
doubled. Which line will be produced?
(1) A (2) B (3) C (4) D (5) E
37) Two blocks of masses 5kg and 3kg, are placed on a horizontal surface as shown in
the figure. The coefficient of friction between the two blocks is 0.5. The coefficient
of friction between the 5kg block and the surface is 0.7. What is the maximum
horizontal force that can be applied to the 5kg block, so that the two blocks move
without sliding against each other?
(1) (2) (3) (4) (5)
38) A, B, C, D, P and Q are points in a uniform electric field. The potentials at these points are
, , and . Find the electric filed at P.
(1)
(2) √
(3)
√
(4) √
(5) √
E
Grade:- 13 (2016) - June - 2016 10 Physics - I
39) A small lead ball falls through a liquid with a speed of 10 cm s-1. If the liquid exerts an upward force
on the ball that is equal to its effective weight. What is the speed with which the ball will move up?
(1) (2) (3)
(4) (5) ;.
40) Two particles, each of mass m, are joined by a light, inextensible
string of length 2a, as shown in the figure. This system is kept on a
smooth surface such that the string remains taught.
A small, constant horizontal force F is applied at the centre of the string, P, causes the two particles
to move towards each other. When the distance between the two particles is , what is the value
of acceleration?
(1)
√ (2)
√ (3)
(4)
√
(5)
√
41) The figure shows a circuit that may be used to compare the
resistance R of an unknown resistor with a 100Ω standard. The
distances from one end of the potentiometer slider wire to the
balance point are 400 mm and 588 mm when X is connected to Y
and Z respectively. The length of the slider wire is 1.00 m. What
is the value of resistance R?
(1) (2) (3) (4) (5)
42) The primary coil of an ideal transformer has 200 turns and is connected to a 15V r.m.s supply. The
secondary coil has 3200 turns and is connected to a resistor of resistance 120Ω, as shown in the
diagram. What are the possible values of the secondary voltage, the secondary current and the
mean power dissipated in the resistor?
Secondary voltage
(V r.m.s)
Secondary current
(A r.m.s)
Power dissipated at the resistor
(W)
(1)
(2)
(3)
(4)
(5)
Grade:- 13 (2016) - June - 2016 11 Physics - I
43) 3/5th portion of a glass vessel is filled with mercury. The coefficient of volume expansion of the glass
and mercury are 9×10-6 oC-1 and 18×10-5 oC-1, respectively. The coefficient of apparent volume
expansion of mercury is
(1)
(2)
(3)
(4)
(5)
44)
A non-uniform thin rod AB of length 1m and mass 2kg is hung using 2 spring balances as shown in
figure (1). When a 2kg mass was hung a distance from A, the two balances showed different
readings. The graph shows the readings of X and Y, when the 2kg mass is hung at different values of
a while keeping the rod horizontal. The distance of the centre of gravity of the rod from A is
(1) (2) (3) (4) (5)
45) In the given circuit, when key K is open, reading of the
ammeter is I. If the key K is closed, which of the following
statements are correct?
(1) If , reading of the ammeter is less than .
(2) If , reading of the ammeter is greater than .
(3) If , reading of the ammeter will be zero.
(4) Reading of the ammeter won’t change.
(5) If reading of the ammeter will be zero.
46) A vessel contains a mixture of air and water vapour. at constant temperature its pressure, P, was
measured by changing it volume, V. Which graph best represents the P vs
curve that was
obtained?
Fig - Fig -
Grade:- 13 (2016) - June - 2016 12 Physics - I
47) A “U” tube containing water and coconut oil is kept in a place with
still air, as shown in the figure. (Density of water - 1000 kgm-3,
density of coconut oil - 800 kgm-3, density of air - 1 kgm-3) To
maintain the liquid levels in the two arms of the “U” tube at the
same horizontal level,
(1) Air should be blown horizontally, in the direction into the
paper above the arm X with a speed of 20ms-1.
(2) Air should be blown horizontally, in the direction into the
paper above the arm Y with a speed of 20ms-1.
(3) Air should be blown horizontally, in the direction into the paper above the arm X with a speed
of 10ms-1.
(4) Air should be blown horizontally, in the direction into the paper above the arm Y with a speed
of 10ms-1.
(5) Air should be blown horizontally, in the direction into the paper above the arm X with a speed
of 5ms-1.
48) A screen and an object are separated by a distance . When a converging lens is placed between
them, the magnification by the lens was m. What is the focal length of the lens?
(1)
(2)
(3)
(4)
(5)
49) Two hollow spheres, A and B, of the same thickness but made of different materials, are filled with
ice cubes. The inner radius of A is twice that of B. When compared to the radius, the thickness of
these spheres can be neglected. The ratio between the time taken for the complete melting of ice in
A and that in B is 25:16. What is the ratio between the thermal conductivities of A and B?
(1) (2) (3) (4) (5)
50) A sound source placed very far from the observer emits a sound with frequency . The sound source
starts to move towards the observer with a constant acceleration . A short (just) while after the
source starts moving, what is the frequency of the sound perceived by the observer? (the speed of
sound in air is )
(1)
(2)
(3)
(4)
(5)
Grade:- 13 (2016) - June - 2016 1 Physics - II(A)
Part - II A
Structured Essay
Answer all four question on this paper itself
1) .
a) When a rigid object is taken far away from the Earth’s surface, will there be a change in its center of
gravity and center of mass?
Center of gravity – ........................................................................................................................
Center of mass – ........................................................................................................................
b) Figure (I) shows a uniform cylinder of length and diameter . Denote the
centre of gravity G, of this cylinder.
c) The cylinder is kept on a rough surface. The surface is slowly inclined.
Consider that slipping does not occur.
i) Figure (II) shows the position when the cylinder is about to tilt. Draw
the line of action of gravitational force at this instant.
ii) Find θ in terms of and , for the instant when the cylinder tilts.
................................................................................................................... ̀
...................................................................................................................
d) The leaning tower of Pisa, shown in figure (III) can be
roughly considered as a cylinder. The height of this
tower is 56m and the diameter of its base is 16m. This
tower is gradually approaching a state which will cause it
to fall. Upon reaching which value of θ will this tower
fall?
...........................................................................................
...........................................................................................
...........................................................................................
G.C.E. A/L Examination June - 2016
Conducted by Field Work Centre, Thondaimanaru
In Collaboration with
Zonal Department of Education Jaffna.
Three :- Three hours Grade :- 13 (2016) Physics - II
FWC
Fig -
Fig -
Fig - I
Grade:- 13 (2016) - June - 2016 2 Physics - II(A)
e) Figure (IV) shows a man horizontally pushing a 40kg
cylinder placed on a rough, horizontal surface.
i) Denote the horizontal forces acting on the cylinder and man, separately on the figures.
ii) The graph between the force, F, applied to the cylinder by man and the frictional force, X,
acting on the cylinder, was plotted as shown below.
Find the coefficients of static and dynamic friction between the cylinder and the surface.
Coefficient of static friction – ............................................................................................
............................................................................................
............................................................................................
Coefficient of dynamic friction – ............................................................................................
............................................................................................
............................................................................................
iii) For the man to continuously push the cylinder without slipping, what should be his least
weight? (Consider that the coefficient of friction between the man’s legs and the surface is 0.2,
and that the cylinder moves with a constant velocity)
..........................................................................................................................................................
..........................................................................................................................................................
Fig -
Grade:- 13 (2016) - June - 2016 3 Physics - II(A)
2)
a) Why is a steam generator used to heat the end X?
.................................................................................................................................................................
.................................................................................................................................................................
b) Should steam be sent in from above or below? Give reason.
.................................................................................................................................................................
.................................................................................................................................................................
c) Holes are made in the rod, a little mercury is poured into them, and then the thermometers are
kept. What is the reason for this?
.................................................................................................................................................................
.................................................................................................................................................................
d) Which property of mercury enabled it to be chosen for the action mentioned in part (c)?
.................................................................................................................................................................
e) What is the name of the part denoted by Z (shown within broken lines)? What is its use?
.................................................................................................................................................................
f) Why is cool water sent in the opposite direction to the heat flow?
.................................................................................................................................................................
.................................................................................................................................................................
g) The cool water tube is removed and an ice-water mixture is attached at that point. At stable state,
the ice dissolves at a rate of per minute. (The latent heat of fusion of ice is ) The
readings of the thermometers T1 and T2 are and , respectively. The distance between
these two thermometers is . The cross sectional area of the rod is . Find the thermal
conductivity of the material of the rod. (Neglect the heat loss to the environment)
.................................................................................................................................................................
.................................................................................................................................................................
.................................................................................................................................................................
Steam
Grade:- 13 (2016) - June - 2016 4 Physics - II(A)
3) a) What type of waves forms on a violin string? To which type do the sound waves reaching our ears
belong?
.................................................................................................................................................................
.................................................................................................................................................................
b) Even though the same not is played on a violin and a flute, the ear can distinguish them separately.
Which property of sound is identified here?
.................................................................................................................................................................
c) What causes this difference?
.................................................................................................................................................................
d) The figure shows a sonometer. The center point of the wire AB is vertically plucked. Is the wave
formed on the wire longitudinal or transverse?
.................................................................................................................................................................
e) How does the air in the sonometer box gain the energy to vibrate?
.................................................................................................................................................................
.................................................................................................................................................................
f) On the figure given below, draw the wave form of a wave that will have the maximum possible
wavelength on wire AB.
g) If a tuning fork has been given to you, explain how you will make the wire vibrate without plucking
it.
.................................................................................................................................................................
.................................................................................................................................................................
h) Give the equation for the wire’s fundamental frequency, , in terms of tension , length , and
mass per unit length of the wire .
.................................................................................................................................................................
i) If the mass of the wire , tension in the wire and the fundamental frequency
of the wire , then find the length of the wire.
.................................................................................................................................................................
.................................................................................................................................................................
Grade:- 13 (2016) - June - 2016 5 Physics - II(A)
4) The potential divider shown in the figure supplies varying potential (VXY) across its terminals X and Y. R
is a 5kΩ variable resistor with a sliding contact P. E is a 6V electric cell with negligible internal
resistance.
a) To verify Ohm’s law by using the above potential divider, the following equipments are given. An
ammeter with negligible internal resistance, a voltmeter with 10MΩ internal resistance and a 60Ω
resistor.
i) Complete the circuit using the equipments given above, and denote the positive terminals of
the ammeter and voltmeter using the symbol.
ii) A rheostat is given instead of the 5kΩ resistor. Denote the terminals of the rheostat as X, Y and
Z in the given space.
iii) Suggest a suitable value for the full scale deflection of the ammeter.
..........................................................................................................................................................
..........................................................................................................................................................
iv) What is the advantage of using an ammeter which has the full scale deflection that you
mentioned above?
..........................................................................................................................................................
..........................................................................................................................................................
v) Draw the rough sketch of the graph that you would expect from this practical.
Grade:- 13 (2016) - June - 2016 6 Physics - II(A)
vi) Will there be any change in the value calculated for R, if the internal resistance of the ammeter
is not zero? Explain.
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
vii) If the ammeter has internal resistance, draw the rough sketch of the graph you would expect in
the same graph, and mark it as A1.
b) If a torch bulb was used instead of the 60Ω resistor, the given graph was obtained.
i) What is the reason for the characteristics of the filament bulb to deviate from the Ohm’s
law?
..........................................................................................................................................................
..........................................................................................................................................................
ii) A torch bulb has been rated as 6V, 0.36W. When the bulb operates as rated, calculate the
resistance of the filament.
..........................................................................................................................................................
..........................................................................................................................................................
iii) If a semiconductor is used instead of a filament, draw the curve for this situation on the
same graph and mark it as A2.
Grade:- 13 (2016) - June - 2016 1 Physics - II (B)
Part - II - Essay
Answer only four questions
5)
As shown in figure (I), a 200m racing track has two straight sections and two semicircular sections. The
centre X, of a straight track is the starting and finishing point. A 4×200m relay event took place in this
track. The speed-time graph of group G, which participated in the relay, is given in figure (II). The area
MN on the track is where the baton is passed on to the next player. In the graph, 21s, 40.5s and 60.5s
denote the time when baton is transferred.
G.C.E. A/L Examination June - 2016
Conducted by Field Work Centre, Thondaimanaru
In Collaboration with
Zonal Department of Education Jaffna.
Grade :- 13 (2016) Physics - II
FWC
Fig -
Fig -
Grade:- 13 (2016) - June - 2016 2 Physics - II (B)
a) i) Separately find the distance that each of the first three runners ran.
ii) If the distance ran by the last runner is 202m, find the time taken to complete the 4×200m
relay race.
iii) Of these four runners, which one had the highest average speed?
iv) What is the total time taken for the first athlete to run the two semicircular portions of the
track?
v) If the maximum speeds of these athletes do not change, give two strategies that they can
follow to finish the race in minimum time.
b)
i) How does a runner obtain the force he needs to run? Copy the figure of the
runner shown here onto your answer script and denote that force on the athlete.
ii) If the mass of the first athlete is 60kg, during the first 1.5s what is the magnitude of the force
mentioned in b(i)?
iii) What is the magnitude of the angle that the athlete makes with the horizontal?
iv) When the athlete runs on a straight track, why does he run with uniform speed despite
obtaining the force mentioned in b(i)?
v) When this first athlete runs on the semicircular track, what is the centripetal force acting on
him? How does he obtain this force?
c) Figure (III) shows a section of the speed-time graph of the first athlete of the H team which takes
part in this race. At which second will this athlete catch up with the first athlete of the G team?
Grade:- 13 (2016) - June - 2016 3 Physics - II (B)
6) a) Endoscopes are commonly used in medicine for the purpose of viewing some internal organs. One
end of the endoscope has a small lens. The image of the internal organ formed by this lens is
conducted by total internal reflection, through the optical fibers in the endoscope, to the other end
of the endoscope. The photons in the laser light have the same energy and they all travel in parallel
to one another. As a result, Laser light is highly monochromatic and parallel. In conjunction with a
laser, the endoscope may also be used for surgery.
i) Explain how an endoscope allows a surgeon to view the stomach.
ii) What properties of laser light make it suitable to be used as a scalpel?
iii) Suggest a physical process which occurs in soft tissue exposed to laser light to enable the light
to act as a scalpel.
b) In a process known as spot welding, a pulsed laser is used to repair small tears in the retina. The
power of the laser light prior to entry into a bundle of optical fibres is 125W. 40% of the incident
power is not transmitted through the fibres.
i) Calculate the light intensity in W mm-2 of the laser beam when it is focused in to an area of
of the retina.
ii) The duration of each pulse of laser light is . Calculate the energy supplied to the retina in
one pulse.
Grade:- 13 (2016) - June - 2016 4 Physics - II (B)
c) The figure illustrates laser light being used to destroy unhealthy tissues.
i) Explain why one some tissue in the laser beam is destroyed.
ii) Suggest one advantage of using a lens of short focal length for the removal of a thin layer of
tissue.
7) Read the paragraph carefully and answer the questions given below.
The human heart is the pump that circulates blood throughout the body. The left ventricle of the heart
pumps blood into the aorta, which is the main artery of the human body. This blood is then distributed
among several arteries and capillaries and sent to the different parts of the body. The normal heartbeat
for a person at rest is 70 beats/minute.
The Poiseuille’s equation is often used for approximate calculations of blood flow in human body. The
flow of blood through vessels need not be a streamline flow. An empirical equation could be used to
check whether the flow is streamline or not. If the liquid of viscosity η and density ρ, flows through a
pipe of diameter D with velocity v, the Reynolds number NR will be defined as follows.
It has been verified experimentally that during streamline flow, the number NR will be less than 2000.
a) .
i) Identifying the symbols, write down the Poiseuille’s equation for the flow of viscous liquid
through a tube.
ii) State two reasons why Poiseuille’s equation is not strictly valid for the flow of blood through
arteries.
b) Suppose that a volume of 70cm3 blood is pumped into the aorta on each beat of the heart.
i) Calculate the average volume of flow rate of blood through the aorta when the person is at
rest.
ii) If the diameter of the aorta is 1cm, calculate the average speed of blood in the aorta. State any
assumptions that you have made.
Grade:- 13 (2016) - June - 2016 5 Physics - II (B)
c) i) Verify that the Reynolds number NR is dimensionless.
ii) Justify, showing necessary calculations, that the blood flow in part (b) is laminar. Assume that
the viscosity and density of blood at body temperature are and
respectively.
d) Now, consider the flow of blood through a horizontally situated artery with uniform cross section,
having radius 2mm. The length of the artery is 20cm. the average rate of blood flow has been
estimated to be .
i) Calculate the pressure difference between the two ends of the artery.
ii) Calculate the rate of work done by the heart in pumping blood through this artery.
8) This question is about the design of a new propulsion system for driving a boat at sea.
a)
i) Write the equation for the force acting on a moving charge placed in a magnetic field.
ii) Write the equation for the force acting on the current carrying conductor placed in a magnetic
field.
b) The first proposal – As shown in figure (I) copper bar is fixed under the boat and a large current is
passed through it. A large electromagnet produces a vertical magnetic field, as shown in the figure.
i) State the direction of the force on the bar when the current is flowing as shown in the diagram.
ii) Which law did you use in part (i)?
iii) Give two ways of increasing the force on the bar.
iv) Explain briefly whether this system will work.
c) The second proposal - As shown in figure (II), this proposal suggests passing a current through the
water instead of through the copper bar using an electrode system. Each electrode face has a
surface area of and they are apart. The drag force on the boat, which has a mass of
, is when it moves at . The current used is to be 1000A.
i) What is meant by ionization? Explain how this enables a current to flow in seawater.
ii) Explain why the boat moves when a current is passed through the seawater.
iii) What is the strength of the magnetic field required so that the thrust is sufficient to maintain a
constant speed of ?
Fig - I Fig - II
Grade:- 13 (2016) - June - 2016 6 Physics - II (B)
9) Answer either part (A) or part (B).
(A)
You may have seen a sign at the bottom of an electricity pylon saying “Danger. High voltage”.
Power is transmitted around the country at voltages as high as 400 000V. This has a very good
reason- to save a lot of energy.
Figure 1 suggests two ways of transmitting 25MW power from a Yorkshire power station to the
midlands.
a)
i) Power can be transmitted through the power cables at a supply voltage of 25000V.
ii) Power can be transmitted through the power cables after the voltage is stepped up to
250000V.
How much power would be wasted in heating the cables in each case, given that 200km of
cable has a resistance of 10Ω.
b) .
i) Explain why the electricity supply in your home is AC rather than DC.
ii) Use the data in figure 1 to calculate the voltage at each point X and Y.
c) The figure shows how electric power is transmitted
from generating stations to consumers on high-
voltage overhead power lines, supported by metal
pylons, which are earthed. Each conductor is
suspended vertically below the pylon structure by an
insulator which is 3.5 m long. The distribution voltage
is 380kV r.m.s. It may be assumed that the voltage
applied to each conductor has sinusoidal waveform.
Fig - I
cU II
Grade:- 13 (2016) - June - 2016 7 Physics - II (B)
i) Calculate the peak voltage supplied to each of the conductors.
ii) Estimate the magnitude of the maximum electric field strength between a conductor and the
pylon structure, if the field could be assumed to be uniform. (Neglect the magnetic field
induced in one conductor by another)
d) Under certain atmospheric conditions it is possible to hear sharp crackling sounds coming from the
region around the conductors.
i) State the atmospheric conditions under which the effect will become more pronounced.
Explain your answer.
ii) Suggest an explanation for this effect.
9) (B)
i) Mention how the junction field effect transistor (JFET) differs from a bipolar transistor in each of
the following factors.
i) Number of p-n junctions
ii) Charge carriers
iii) Whether the factor controlling the function is potential difference or current flow
ii)
i) Draw the output characteristic curves of an -channel junction field effect transistor.
ii) Which factor is kept constant when drawing a characteristic curve of this output?
iii) Denote the linear region, saturated region and cutoff region on your graph.
iii) Figure (I) shows a circuit used to bias an -channel
junction field effect transistor. Resistors RG and RS are
connected to the earth and resistor RD is connected
to the direct power supply VDD.
i) Reason out and explain that gate voltage VG=0.
ii) Show that drain current
.
iii) Write an equation for the drain-source voltage, VDS, in terms of VDD, ID, RD and RS.
iv) The transfer characteristics curve of this junction field effect transistor is shown in figure (II).
Grade:- 13 (2016) - June - 2016 8 Physics - II (B)
Consider that the biasing condition in part (b) is to be arranged such that ID=6mA. To achieve this,
the following conditions are maintained. VDD=10V, RD=500Ω and RG=1MΩ.
i) Find the value of the pinch off voltage (VGS(off)) and the maximum value of the saturated drain
current (IDS(sat)).
ii) Copy figure (II) onto your answer script and denote the operating point of this biased state as
Q.
iii) Calculate the value of RS and from that, calculate VDS.
10) Answer either part (A) or (B).
(A)
A cylinder and piston of a vehicle are shown in the diagram. The initial volume and temperature of
the system are and respectively. The area of cross section of this piston is .
Air is taken into it with a pressure of . the total weight of the cylinder and its content is
. Its specific heat capacity is . Now, heat is produced by burning the air within
the cylinder. Air, which is taken in at reaches a temperature of 177oC, pushes the piston,
and is then released from the system. Fresh air is taken into the cylinder at and the system
returns to its initial volume and pressure. This process happens 750 times per minute. From ,
the system reaches a stable state of in one minute. For the following process, the piston is
at 177oC.
Universal gas constant
The molecular mass of air
The specific heat capacity of air
i) What is the mass of air trapped in the piston each time?
ii) Find the heat gained by the air in one minute.
iii) Find the heat gained by the cylinder system in one minute.
iv) What is the rate of heat supplied to this system? (Neglect the heat loss to the environment)
v) What is the additional pressure exerted on the piston when air inside is heated from 27oC to
177oC?
vi) The piston is pushed outwards so that the pressure inside returns to . At the
constat temperature (177oC) what is the increase in volume of the gas?
vii) What is the rate of work done by the gas?
Piston
Cylinder
Grade:- 13 (2016) - June - 2016 9 Physics - II (B)
viii) Water at 27oC is allowed to flow around the cylinder in order to maintain its temperature
stably at 177oC. When it flows completely around the cylinder and leaves, its temperature is
87oC. What is the rate of mass flow of the water? (Assume that the cylinder continuously
gains heat as mentioned in part (c). The specific heat capacity of water is )
ix) In the appliance mentioned in part (h) (radiator) why is water allowed to flow through a long
tube that is folded many times?
x) What is the property of water that caused it to be selected in part (h)?
10) (B) Stars glow spontaneously when the nuclear energy in them is converted to other forms, such as
heat energy and light energy, due to nuclear fusion reactions. Sun is the closest star to Earth.
During the nuclear fusion reaction taking placing in the sun, four hydrogen atoms are converted
into one helium atom and two positrons (e+).
When heavy, unstable atoms are hit by neutrons moving with sufficient velocity, nuclear fission
occurs. During nuclear fusion and nuclear fission reactions a part of the mass is destroyed and
converted to energy according to the following equation. E = Δmc2. Δm is the destroyed mass,
and c is the speed of light. (c = 3×108ms-1)
a)
i) Write two differences between nuclear fusion and nuclear fission.
ii) Write the equation of nuclear reaction for the energy emitted from the sun.
iii) Calculate the amount of energy released during the nuclear fusion of hydrogen atoms. The
masses of hydrogen, helium and positron are 1.007825u, 4.002603u and 5.55×10-4u
respectively.
1u = 1.66×10-27kg = 931MeV/C2 (1eV = 1.6×10-19J)
iv) At which rate should hydrogen be consumed in order to produce energy at a rate of 1MW?
b)
i) During nuclear fission reactions, instead of protons, why are neutrons used to collide with the
atoms?
ii)
Mass of
Mass of
Mass of
Mass of
Avogadro’s number
Relative atomic mass of U
Calculate the number of neutrons released in the above reaction.
iii) Calculate the mass reduction occurring during one reaction.
iv) How much energy is produced during one reaction?
v) If 10% of the total energy released is converted to heat energy and this, in turn, is converted
into electricity with 25% efficiency, what is the mass of Uranium used in 1s to produce 300MW
of electricity?