CAPE PHYSICS MULTIPLE CHOICE

UNIT 2

MODULE 1

ELECTROSTATICS, ELECTRICITY, ELECTORMAGNETISM

(1) A pair of parallel plates has a potential difference of 12V across them and is 15cm apart. What is the electric field strength between the plates?

[A] 0.8V/m

[B] 180V/m

[C] 1.8V/m

[D] 80V/m

(2) An LDR has a function of 50KΩ in the dark and 10KΩ in the light. What will the voltmeter reading be when in the dark? Assume the voltmeter is ideal.

[A] 10V

[B] 6V

[C] 2V

[D] 3V

(3) Kirchoff’s first law is as a consequence of the conservation of?

[A] Mass

[B] Power

[C] Charge

[D] Energy

(4) What is the effective resistance between points X and Y in the following diagram?

[A] 9.0Ω

[B] 0.9Ω

[C] 5.2Ω

[D] 3.7Ω

(5) Which of the following diagrams best represents the electric field due to a point positive charge?

(6) An electron is placed at rest in an electric field of fluid strength1.2 X 103Vm

.

What is the initial force on this electron?

[A] 1.92 X 10−16N

[B] 1.33 X 10−16N

[C] 1.92 X 10−22N

[D] 1.33 X 10−22N

(7) Kirchoff’s second law is as a consequence of the conservation of?

[A] Energy

[B] Charge

[C] Mass

[D] Power

(8) A length of wire 1m long and 1mm in diameter is used in a potential circuit. If the resistance of the wire is 6.5Ω, find the resistivity of the wire.

[A] 2.04 X 10−5Ω.m

[B] 5.1Ω.m

[C] 5.1 X 10−6Ω.m

[D] 2.04Ω.m

(9) Which of the following diagrams best represents the magnetic field around a straight wire carrying a current into the page?

(10) A student wishes to make a capacitor with a capacitance of 1000µF. If the area of the plates is 5.65 X 10−2m2 and the space between the plates is air, what must be the separation of the plates?

[A] 0.5mm

[B] 5.0mm

[C] 1.0mm

[D] 2.5mm

(11) A capacitor has a capacitance of 10000µF. How much energy is stored in the capacitor when a potential difference of 12V is applied across the plates?

[A] 0.06J

[B] 1.44J

[C] 14.4J

[D] 0.072J

(12) The diagram shows a piece of wire 0.5m long and moving with a speed of 3.0ms−1 perpendicular to a magnetic field of field strength 1.5m T. What is the e.m.f induced across the ends of the wire?

[A] 4.5 X10−3V

[B] 2.25 X 10−3V

[C] 7.5 X 10−3V

[D] 2250V

(13) A flat circular coil has a radius of 4.0cm and 150 turns. If a current of 3.0A is passed through the coil, what is the magnetic field strength at the centre of the coil?

[A] 7.07mT

[B] 707mT

[C] 0.56mT

[D] 56mT

(14) A wire of length 30cm is in a magnetic field of strength 3.5mT and makes an angle of 60° with the field. If the wire is carrying a current of 2.5A, what is the magnetic force on the wire?

[A] 1.31 X 10−3N

[B] 2.27N

[C] 2.27 X 10−3 N

[D] 1.31N

(15) A wire of diameter 1.0mm is carrying a current of 1.5A. If the charge of carriers are electrons and the net drift velocity of the electrons iso .5ms−1, what is the number of conduction electrons per unit volume in the conductor?

[A] 9.52 X 1025

[B] 2.38 X 1025

[C] 6.02 X 1023

[D] 9.52 X 1023

MODULE 2

ELECTRONICS

(16) Which of the following is NOT a property of an ideal op-amp?

[A] It has a very high open-loop voltage gain.

[B] It has very high input impedance.

[C] It takes at least 0.1A from the input current in order to function.

[D] It has very low output impedance.

(17) The diagram shows an inverting amplifier with negative feedback.

If V 3 = ±9V, what is the value of V O?

[A] 9V

[B] 5V

[C] 2.5V

[D] 12V

(18) The following diagram shows a non-inverting amplifier with negative feedback.

Which of the following formulas represents the gain of the amplifier?

[A] 1+R fR i

[B] –R fRi

[C] Ri

R i+R f

[D] 1−RfRi

(19) Which of the following is NOT an advantage of using negative feedback in an op-amp?

[A] The gain is predictable and constant.

[B] Feedback reduces distortion of the output.

[C] Stability in increased.

[D] Feedback increases the gain.

(20) An op-amp operating with negative feedback has a gain of 103 and a band width of 103Hz. What is the band width when the gain is reduced to 10?

[A] 103Hz

[B] 105Hz

[C] 107Hz

[D] 10HZ

(21) All the logic gates can be made by a combination of NAND gates only. Which gate is equivalent to the following diagram? That is, giving the same truth table.

[A] NOR

[B] AND

[C] NOT

[D] OR

(22) All logic gates can be made using a combination of NAND gates only. Which signal gate is equivalent to the following diagram?

[A] EX-OR

[B] OR

[C] AND

[D] NOT

(23) The following is a diagram of a ‘half-adder’. If the A=1 and B=0, what is the value of the ‘sum’ and the value of the ‘carry’?

[A] Sum=0, Carry=0

[B] Sum=1, Carry=1

[C] Sum=1, Carry=0

[D] Sum=o, Carry=1

(24) The majority charge carriers is an n-type material is:

[A] Protons

[B] Electrons

[C] Holes

[D] Neutrons

(25) Which of the following diagrams best represents the depletion layer at a p-n junction?

(A) Note: represents holes

represents electrons

(B)

( C)

(D)

(26) Which of the following graphs represents a half wave rectified sinusoidal a.c using a diode?

(27) A sinusoidal signal has a peak voltage of 5.0V. What is the r.m.s value of this signal?

[A] 6.25V

[B] 7.07V

[C] 2.50V

[D] 3.54V

(28) One advantage of transmitting electrical energy at high voltages is:

(A) Less energy is lost in the transmission lines

(B) It is difficult for anyone to steal current from these high tension wires

( C) It can be stepped down easily

(D) Thinner cables can be used.

(29) An ideal transformer has 600 turns in the primary windings and 40 turns in the secondary windings. If the current in the primary is 5.0 A and the voltage across the primary is 120 V, what is the current in the secondary and the voltage across the secondary?

Current in Secondary/A

Voltage across secondary/V

A 1 15B 60 8C 8 75D 75 8

(30) Which of the following graphs represents the I-V characteristics of a p-n junction diode?

(A) (B)

I I

V V

I I

( C) (D)

V V

UNIT 2

MODULE 3

Atomic Structure and Nuclear Physics

(31) Which of the following best describes "work function" in relation to the photoelectric effect?

(A) The energy of a photon

(B) The maximum kinetic energy of the electrons

(C) Minimum energy required to just remove electrons from a surface

(D) The energy provided be the stopping potential

(32) Electromagnetic radiation of wavelength 200 nm strikes a surface. What is the energy of one photon of this radiation?

(A) 9.95 x 10-19 J

(B) 1.99 x 10-18 J

(C) 3.32 x 10-19 J

(D) 9.95 x 10-33 J

(33) With respect to the photo electric effect, which of the following best defines "cut-off wavelength" ?

(A) Minimum wavelength for photoelectrons to be emitted

(B) The wavelength of the incident radiation

(C) The wavelength that gives the maximum K.E to the electrons

(D) Maximum wavelength for which photoelectrons are emitted

(34) The diagram below shows the x-ray spectrum obtained when a potential difference V is applied across the anode /cathode of an x-ray tube, showing the Kα

and Kβ wavelengths positions. The horizontal units are relative units.

I

Kβ Kα

1 2 3 4 λ

Which of the following graphs best represents the spectrum when the P.D applied is 2 x V ( ie the voltage is doubled)

(A)

Kα

Kβ V

2 V

1 2 3 4 λ

(B)

I Kα

Kβ 2V

V

1 2 3 4 λ

(C)

I Kα

Kβ

2V

V

1 2 3 4 λ

(D) Kβ

I Kα

2V

V

1 2 3 4 λ

(35) Which of the following BEST describes the conclusion arrived at from Millikan's oil drop experiment?

(A) An oil drop can be made to attain terminal velocity

(B) The charge of an electron is 1.6 x 10-19 C

(C) Charge is quantized

(D) Oil drops can be charged

(36) The Helium atom has a mass of 4.0026 u. Its constituents consist of two neutrons, each of mass 1.0087 u and two protons, each of mass 1.0078 u. What is the binding energy of helium? (Take 1 u ≡ 931 Mev )

(A) 28.3 Mev

(B) 30.0 Mev

(C) 26.6 Mev

(D) 27.9 Mev

(37)When a radium atom disintegrates emitting an α- particle, its mass decreases by 8.6 x 10-30 Kg. What is the energy equivalent of this mass loss?

(A) 4.84 x 10-13 J

(B) 9.31 x 10-13 J

(C) 8.00 x 10-19 J

(D) 7.74 x 10-13 J

(38) Which of the following graphs BEST represents the relationship between binding energy per nucleon and nucleon number? The vertical axis is "Binding energy per nucleon in Mev" and the horizontal axis is "Nucleon number".

(A)

20

20 40 60 80 100

(B)

20

20 40 60 80 100

(C)

9

20 40 60 80 100

(D)

9

20 40 60 80 100

(39) A Radioactive source has an activity of 8.0 x 106 Bq at 6:00 am on a particular day when the temperature is 200 C. If the source has a half life of 8 hours, what would be the activity at 2:pm the next day (32 hours after), when the temperature rises to 300 C ?

(A) 2.0 x 106 Bq

(B) 5.0 x 105 Bq

(C) 1.0 x 106 Bq

(D) 4.0 x 106 Bq.

(40) At a certain time a radioactive source has an activity of 4.5 x 106 Bq and the number of atoms present is 9.0 x 1010 atoms. What is the half-life of the source?

(A) 1.39 x 104 S

(B) 3.47 x 10-5 S

(C) 5.00 x 10-5 S

(D) 2.00 x 104 S

(41) A photosensitive surface has a threshold wavelength of 650 nm. It is radiated with e.m. radiation of wavelength 400nm. What is the stopping potential for this incident radiation?

(A) 4.8 V

(B) 2.5 V

(C) 3.8 V

(D) 1.2 V

(42) What does the observation of a line emission spectrum suggest about the atom?

(A) Energy can be radiated from an atom when electrons move from a higher to a lower energy level

(B) The atom has protons, neutrons and electrons

(C) The atom is capable of absorbing energy as well

(D) The existence of discrete electron energy levels within the atom

(43) Which of the following suggests that a beam of electrons can also behave as a wave ?

(A) The electrons can be reflected on hitting a surface

(B) The beam of electrons produces a diffraction pattern when it passes through a suitable diffraction grating.

(C) The electron beam can be polarized

(D) The electron beam can be stopped by 2 cm of lead.

(44) Which of the following suggests that electromagnetic radiation can behave like a particle?

(A) The radiation can display an interference pattern when passed through Young's double slit

(B) The e. m. radiation can be polarized

(C) The radiation can cause pressure on a surface

(D) Any frequency of an e. m radiation can produce the photoelectric effect.

(45) Which of the following pairs of atoms are Isotopes, given the atoms are as

follows: 147 A, 14

8 B, 157 X, 15

9 Y ?

(A) 147 A, and 14

8 B,

(B) 147 A and 15

7 X

(C) 157 X and 15

9 Y

(D) 159 Y and 14

8 B

(46) A radioactive source has a half-life of 2 years . What would be the ratio of the number of atoms present after 5 years to the number of atoms originally present?

(A) 0.177

(B) 0.167

(C) 0.082

(D) 0.368

(47) The P.D. across an X-ray tube is maintained at 100 KV. If an electron gives up all its kinetic energy in a single encounter with a target atom so that all the energy is converted into X-rays, what is the minimum wavelength of the X-rays?

(A) 1.24 x 10-10 m

(B) 1.98 x 10-11 m

(C) 1.24 x 10-11 m

(D) 1.98 x 10-10 m

(48) A sodium ion is represented by the symbol 2411 Na+ . Which of the following

best describes the composition of the atom?

It has :

(A) 11 protons, 11 electrons and 13 neutrons

(B) 11 protons, 10 electrons and 13 neutrons

(C) 13 protons, 12 electrons and 11 neutrons

(D) 13 protons, 11 electrons and 11 neutrons

(49) Which of the following is the best reason why α- particles radiation is the most dangerous radiation to living cells?

(A) They are strong ionizers

(B) They have the greatest mass

(C) They travel in thick straight lines

(D) They cannot penetrate the living cells

(50) A G.M. tube can be used to detect radiation from a radioactive source. The tube contains Argon and Bromine gases at low pressure. Which of the following best describes the role played by each of these gases?

Argon BromineA Acts as a quenching agent Ionize to produce ion - pairsB Ionize to produce ion - pairs Ionize to produce ion - pairsC Acts as a quenching agent Acts as a quenching agentD Ionize to produce ion - pairs Acts as a quenching agent