Physics II

Time allowed : 3 hours.

SECTION A – Multiple-choice Questions – Answer ALL Questions.

SECTION B – Answer Any THREE Questions.

INSTRUCTIONS FOR SECTION A

1. Read carefully the instructions on the Answer Sheet and insert the information required in the spaces provided.

2. All the answers should be marked on the Answer Sheet.

3. Note that you may only mark ONE answer to each M.C. question. Two or more answers will score NO MARKS.

4. All questions carry equal marks. No marks will be deducted for wrong answers.

Section A (67.5 M)

There are 45 questions in this section. Answer ALL questions. Each question is followed by five suggested answers. Select the best answer in each case. You should spend 1 hour and 45 minutes on this section. When necessary, take velocity of light in air = 3 x 108 m s-1 and acceleration due to gravity = 10 m s-2.

  1. An object of mass 3 kg placed on a smooth plane inclined at 30o to the horizontal is connected by a light string passing over a frictionless pulley to another object of mass 2 kg, as shown below.

When the system is released, what will be the tension in the string?

  1. 18 N
  2. 20 N
  3. 24 N
  4. 25 N
  1. A car of mass m travels up a road inclined at  to the horizontal, as shown below.

Neglecting the power required to overcome frictional forces, what is the total instantaneous power needed to maintain the car’s motion when the car has an instantaneous velocity v and an acceleration a?

A.m(g + a)v sin

B.m(g sin+ a)v

C.m(g + a)v cos

D.m(g cos+ a)v

  1. A stone is thrown horizontally from the top of a cliff with a speed of 40 m s-1. If air resistance is negligible, what will be the speed of the stone when it hits the surface of the sea 3.0 s later?
  2. 30 m s-1.
  3. 40 m s-1.
  4. 50 m s-1.
  5. 70 m s-1.
  1. The graphs show the relationship between pairs of quantities in four different situations.

In which one of the graphs does the shaded are NOT represent work or energy?

  1. expansion of a gas
  2. charging a capacitor
  3. stretching a spring
  4. motion of a spacecraft away from the Earth
  1. People inside a car are protected from the electric fields associated with lightning. Many parts of stereo components are contained in metal boxes. What do these two examples demonstrate about the electric field inside a closed metal container?
  2. zero
  3. opposite to the field outside
  4. equal to the field inside
  5. half the field outside
  1. An alpha-particle traveling at a speed v collides head-on with a stationary radon gas nucleus of nucleon number 222. If the collision is perfectly elastic, which one of the following correctly describes the outcome?
  2. The alpha-particle comes to rest and the radon nucleus moves on at a speed v.
  3. The alpha-particle rebounds at a speed v and the radon nucleus moves on at speed v.
  4. The alpha-particle rebounds at a speed v/2 and the radon nucleus moves on at a speed v/2.
  5. The alpha-particle rebounds at a speed nearly equal to v and the radon nucleus moves on at a speed much less than v.

  1. A harbour which has a 10 metre tide has a bar which is 5 m below the surface at low water. On a particular morning low tide is at 2 a.m. and high tide at 8.15 a.m. A ship which needs a minimum of 7.5 m of water in order to float is to leave as soon as possible on that day. Assuming that tidal motion is simple harmonic, calculate the time at which it should leave.
  2. 3.34 a.m.
  3. 4.05 a.m.
  4. 4.35 a.m.
  5. 5.45 a.m.
  1. A flywheel of mass 10 kg and diameter 0.4 m is mounted on a frictionless bearing. A mass of 5 kg is attached to a thin string wound round the flywheel and the system is held at rest. The mass is then released. What is the speed of the 5 kg mass after it has fallen 1 m?
  2. 2.58 m s-1.
  3. 3.16 m s-1.
  4. 5.77 m s-1.
  5. 4.77 m s-1.
  6. The disc shown below is rotated in turn about the four different axes:
  1. XY
  2. WZ
  3. An axis through O and perpendicular to the plane of the disc
  4. An axis through Y and perpendicular to the plane of the disc.

About which axis will the disc have the least moment of inertia?

  1. Two neighbouring molecules with separation r experience a force F between them. The graph below shows how F varies with r.

Which of the following statements is/are correct?

(1)Hooke’s law follows from the linearity of the region LMN.

(2) is the equilibrium separation of the molecules.

(3)Thermal expansion can be explained by the fact that the curve NPQ is not symmetrical about P.

  1. 1, 2 and 3
  2. 1 and 2 only
  3. 2 and 3 only
  4. 1 only
  1. Two metal rods of the same Young modulus Y and the same cross-sectional area A, but of different lengths L and 2L respectively, are joined together end-to-end to form a rod of length 3L. What are the Young modulus and the force constant of the composite rod?

Young modulus / Force constant
A / 2Y / 3AY/L
B / 2Y / AY/3L
C / Y / 3AY/L
D / Y / AY/3L
  1. In a particular process 16 kJ of heat is supplied to a system whilst at the same time 4 kJ of work is done by the system. What is the change in internal energy of the system?
  2. zero
  3. 12 kJ
  4. 16 kJ
  5. 20 kJ
  1. When a gas is below its critical temperature, which of the following is/are correct?

(1)Intermolecular forces are significant.

(2)The gas can be liquefied by applying pressure alone.

(3)Collisions between molecules are not perfectly elastic.

  1. 1 only
  2. 3 only
  3. 1 and 2 only
  4. 2 and 3 only
  1. At 0o C temperature and 1.00 x 105 N m-2 pressure, the density of a gas is 0.179 kg m-3. The r.m.s. speed of the gas molecules at 91o C will be
  2. 231 m s-1.
  3. 470 m s-1.
  4. 1290 m s-1.
  5. 1490 m s-1.

The above figure shows a transverse wave propagating to the right along a string. At the moment shown, which of the labeled particles has its velocity and acceleration in opposite directions?

  1. P
  2. Q
  3. R
  4. S

Three identical long spiral springs are connected respectively to a wall, a light thread and a heavy spring. If a crest-shaped pulse is sent along each spiral spring towards the respective boundary, which of the following diagrams corretly show(s) the reflected pulse? (Transmitted pulse is not shown.)

  1. 1 only
  2. 3 only
  3. 1 and 2 only
  4. 2 and 3 only

In a Young’s double-slit experiment, light of wavelength 400 nm is used. If the path difference between the light from the two slits X and Y to a point P on the screen is 3000 nm, which of the following is/are correct?

(1)P is the 7th dark fringe.

(2)The fringe separation on the screen increases if the light source is moved closer to the slits.

(3)P becomes a bright fringe if light of wavelength 500 nm is used.

  1. 1 0nly
  2. 3 only
  3. 1 and 2 only
  4. 2 and 3 only
  1. A plane transmission grating is placed at the center of a circular 0o – 360o protractor. A beam of monochromatic light is incident normally on the grating. The zeroth-order maximum occurs at a scale reading of 90o and a first-order maximum occurs at a scale reading of 65o. At what scale reading would a second-order maximum be observed?
  2. 148o
  3. 140o
  4. 130o
  5. 58o
  1. A wedge of small angle formed between two plane pieces of glass is illuminated by monochromatic light of wavelength . The width of the Nth fringe is z and it is formed at a distance x from the line of contact of the two pieces of glass. The minimum data required to calculate z are
  2. N, x and
  3. N,  and
  4.  and
  5. x ,  and
  1. In an arrangement for viewing Newton’s rings, which of the following would be observed if water is introduced to the space between the lens and the glass plate?
  2. The rings disappear.
  3. The central spot becomes bright
  4. The separation between the rings increases
  5. The rings shift towards the center.
  1. Two pipes A and B, with pipe A closed at one end and pipe B open at both ends, are sounded to give fundamental notes of the same frequency. The length ratio of pipe A to pipe B is
  2. 1:4
  3. 1:2
  4. 2:1
  5. 4:1
  1. When a parallel beam of white light passes through a glass lens, it is separated into rays of different colours. For which colour of light does the lens have the greatest focal length and for which colour of light does glass have the greatest refractive index?

The lens has the greatest focal length for / Glass has the greatest refractive index for
A / Blue light / Blue light
B / Blue light / Red light
C / Yellow light / Yellow light
D / Red light / Blue light
  1. A converging lens of focal length 12.5 cm is used as a magnifying glass with the final image formed at infinity. If the least distance of distinct of vision is 25 cm, what is the angular magnification?
  2. 1/2
  3. 1
  4. 2
  5. 4

A cell of e.m.f. 1.5 V is connected in series with a variable resistor of resistance R and an ammeter A of resistance 0.5 . By varying R, a series of ammeter readings, I, are taken and a graph of 1/I against R is plotted. The value of the y-intercept is found to be 0.88 A-1. What is the internal resistance of the cell?

  1. 0.59 .
  2. 0.82 .
  3. 1.14 .
  4. 1.20 .

In the above circuit, the cell has e.m.f. 6 V and negligible internal resistance. The resistance of the four resistors R1, R1, R2, R3and R4are 6,, and 2 respectively. The capacitor has capacitance 20 F. At steady state, the charge on the capacitor plate connecting to A is

  1. +80C
  2. +40C
  3. 0C
  4. -40C
  1. Which of the following quantities can be increased by increasing voltage across a metal wire?

(1)the average drift velocity of the conduction electrons

(2)the number of conduction electrons per unit volume

(3)the speed of the electrical signal

  1. 1 only
  2. 3 only
  3. 1 and 2 only
  4. 2 and 3 only
  1. A metal sphere is charged to potential of 100 V. If the charge density on its surface is 6.0 x 10-9 C m-2, find the radius of the sphere.

(Given : permittivity of free space = 8.85 x 10-12 F m-1)

  1. 0.04 m
  2. 0.15 m
  3. 0.21 m
  4. 0.35 m
  1. In an experiment to determine resistance by the ‘ammeter-voltmeter’ method, the voltmeter could be read to ± 0.1 volt and the ammeter to ±0.05 A. Having adjusted the zeros, the observations recorded were 10 V and 4 A.

Calculate the percentage error in the value of the resistance computed from these observations.

  1. 1.25 %
  2. 2.25 %
  3. 4.5%
  4. 5.0%
  1. The diagram shows three long straight wires X, Y and Z normal to the plane of the paper. Wires X and Z each carry current I directed into the plane of the paper and wire Y carries current I directed out of the paper.

Which arrow best shows the direction of the resultant force on wire X?

  1. Using the circuit given below, the neon lamp can be made to flash intermittently.

Which of the following statements about the rate of flashing is/re correct?

The rate of flashing will increase if

(1)C is decreased

(2)R is decreased

(3)The voltage of the supply is increased.

  1. 1 and 2 only
  2. 1 and 3 only
  3. 2 and 3 only
  4. 1, 2 and 3.
  1. A capacitor is to be used to provide smoothing for a half-wave rectifier. In which one of the following circuits is the capacitor correctly connected?
  1. A variable capacitor can be used

(1)as the volume control of an amplifier

(2)to tune a radio to receive a certain channel

(3)to change the power factor of an a.c. circuit

  1. 1 only
  2. 3 oonly
  3. 1 and 2 only
  4. 2 and 3 only
  1. In a step-up transformer the primary current is small when the secondary winding is on open circuit because the primary winding and its core

(1)act as a choke

(2)have a higher resistance than the secondary winding

(3)have a large self-inductance

(4)do not pass a current at all when no current is drawn from the secondary.

Which of the following statements is/are correct?

  1. 1, 2 and 3 only
  2. 1 and 3 only
  3. 2 and 4 only
  4. 4 only.
  1. A d.c. motor is connected to a source of constant voltage V. When rotating at a steady speed, the motor draws a current I and the back e.m.f. developed in its ammature coil is . Which of the following statements is/are correct?

(1)The resistance of the armature coil is V/I.

(2)The mechanical power developed is I.

(3)The back e.m.f. increases with the speed of rotation.

  1. 1 only
  2. 3 only
  3. 1 and 2 only
  4. 2 and 3 only
  1. An inductor of reactance 3 ohm is connected in series with a resistor of value 4 ohm and a sinusoidal current of 2 A is passed through them. What is the applied r.m.s. voltage? What is the power factor?

Applied r.m.s. voltage/V / Power factor
A / 6.0 / 0.75
B / 6.0 / 0.8
C / 10 / 0.75
D / 10 / 0.8
  1. The circuit in the following diagram is connected to the Y-plates of a double-beam CRO (which has no phase correction built in) with its time-base switched to a suitable value. An alternating voltage is applied as shown to the circuit. Identify the trace obtained assuming that the upper-trace is that corresponding to Y1.
  1. The instantaneous value of an alternating current I (in A) at time t (in s) is given by the equation

Which of the following descriptions is/are correct?

(1)The a.c. frequency is 50 Hz.

(2)The value of the current varies between and.

(3)The r.m.s. value of the current is 2 A.

  1. 1 only
  2. 3 only
  3. 1 and 2 only
  4. 2 and 3 only

  1. A proton travels in a circular path in a magnetic field of flux density B.

The same path could be followed by an alpha-particle with the same speed v if the flux density was changed to

  1. 1/2 B
  2. B
  3. 2B
  4. 8B
  1. A circuit is required for doubling the amplitude of a sinusoidal alternating voltage. Which of the following circuits might be suitable?
  1. 1 only
  2. 3 only
  3. 1 and 2 only
  4. 2 and 3 only
  1. A metal has a work function of 4.6 eV. What is the corresponding threshold frequency?

[Given: Planck’s constant = 6.63 x 10-34 J s

Electron charge magnitude = 1.6 x 10-19 C]

  1. 6.9 x 1033 Hz
  2. 1.1 x 1015 Hz
  3. 9.0 x 10-16 Hz
  4. 1.4 x 10-34 Hz
  1. A student performs a photoelectric experiment in which a photoelectric current is observed for all colours of visible light. The student wants to investigate what effect varying the intensity and colour of the incident light has on the photoelectric current and kinetic energy of the photoelectrons. If the brightness of the light is decreased and the colour is changed from yellow to blue, which of the following descriptions is correct?
  2. Photoelectric current and photoelectron energy both decrease
  3. Photoelectric current and photoelectron energy both increase
  4. Photoelectric current decreases and photoelectron energy increase
  5. Photoelectric current increases and photoelectron energy decrease
  1. A photon of energy 1.13 eV is emitted by a hydrogen atom when the electron “jumps” from
  2. n = 6 to n=3
  3. n=3 to n=6
  4. n=5 to n=2
  5. n=2 to n=5

  1. An alpha particle passes without deflection through perpendicular electric and magnetic fields. The magnitude of the magnetic field is 2.20 x 10-2 T. The electric field is maintained by a 3.00 x 102 V potential difference across plates that are 4.00 cm apart. What is the speed of the alpha particle?
  2. 7.50 x 103 m s-1.
  3. 1.36 x 104 m s-1.
  4. 1.20 x 105 m s-1.
  5. 3.41 x 105 m s-1.
  1. The graph shows how the intensity I of a parallel beam of -radiation diminishes as it passes through increasing thickness x of lead.

A straight-line graph could be obtained by plotting

  1. I against 1/x.
  2. I against 1/(x2).
  3. ln I against x.
  4. ln I against lnx.
  1. A nucleus has a nucleon number A, a proton number Z, and a binding energy B. The masses of the neutron and proton are mn and mp respectively, and c is the speed of light.

The mass of the nucleus is given by the expression

  1. (A – Z) mn + Zmp– B/c2.
  2. (A + Z) mn + Zmp+ B/c2.
  3. Amn+ Zmp– B/c2.
  4. Amn + Zmp+ B/c2.

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