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02 AL Physics/M.C./P.1
2002 Hong Kong Advanced Level Examination
AL Physics
Multiple Choice Questions
1.
4.
A
Y
B
C
X
A block of mass m falls from rest at A onto
a vertical light spring of force constant k
firmly fixed to the ground. When the
block reaches B, it starts to compress the
spring until it reaches the lowest position
C as shown. Neglecting air resistance and
considering the motion of the block from
A to C, which of the following statement
is/are correct?
Two identical blocks X and Y are
connected by a light spring and the system
is suspended from a fixed support by a
light cord as shown. The system is in
static equilibrium. If the cord is suddenly
cut, what is the magnitude of the
acceleration of each block at that instant?
A.
B.
C.
D.
2.
Acceleration of Y
g
2g
g
2g
(1) The kinetic energy of the block is at a
maximum when it is at B.
(2) The resultant force acting on the
block is zero when it is at C.
(3) The maximum compression of the
mg
spring is greater than
.
k
Two small identical objects P and Q are
released from rest from the top of a
building 80 m above the ground. Q is
released 1 s after P. Neglecting air
resistance, what is the maximum vertical
separation between P and Q in the air?
A.
B.
C.
D.
3.
Acceleration of X
g
g
zero
zero
5m
10 m
35 m
45 m
The SI unit of length, metre, is defined as
n times the wavelength of a certain
orange-red light emitted from a krypton-86
atom. The number n is of the order
A.
B.
C.
D.
104.
106.
108.
1010.
A.
B.
C.
D.
(1) only
(3) only
(1) and (2) only
(2) and (3) only
5.

A bob of mass m is suspended from a
fixed support by a light string. A force F
is applied to the bob (F is not shown in the
figure) so that the string makes an angle 
with the vertical. What is the minimum
value of F required to keep the bob in
static equilibrium as shown?
02 AL Physics/M.C./P.2
mg sin 
mg cos 
mg sin  cos 
mg sin2
A.
B.
C.
D.
9.
6.
P
X
Q
Y
R
Z
An object undergoes a simple harmonic
motion with an amplitude A, and its total
energy is E. What is the displacement of
the object from the equilibrium position
3E
when its kinetic energy is
?
4
A.
P, Q and R are three identical spheres
moving with the same speed along a
smooth horizontal track. They undergo
head-on elastic collisions with spheres X,
Y and Z respectively which are initially at
rest. After collision, P continues to move
in its original direction, Q becomes
stationary while R reverses its motion.
After collision, which sphere (X, Y or Z)
has the greatest magnitude of
B.
C.
D.
A
2
A
4
3A
4
3A
2
10.
(1) momentum
(2) kinetic energy?
A.
B.
C.
D.
7.
(2)
Y
Y
Z
Z
Z
Y
X
Y
0
momentum.
kinetic energy.
velocity.
acceleration.
A.
B.
C.
D.
A particle P is moving in a horizontal
circle in a clockwise direction as shown
(top view). The following diagrams show

the direction of the acceleration a of the
particle. Which of them is/are possible?
(1)
(2)
y
Displacement
Force
Kinetic energy
Speed
x
Acceleration
Displacement
Displacement
Displacement
11.
(3)
a
a
a
P
A.
B.
C.
D.
x
The graph describes the motion of a
simple harmonic oscillator. Which pair of
physical quantities is most likely
represented by variables y and x?
The impulse experienced by an object is
equal to its change in
A.
B.
C.
D.
8.
(1)
y
(1) only
(3) only
(1) and (2) only
(2) and (3) only
P
P
A thin uniform rod of mass 0.1 kg and
length 0.3 m is smoothly hinged at its
lower end as shown. It is then released
from rest from the vertical position. What
is its angular speed, in radian per second,
when it becomes horizontal? (Moment of
02 AL Physics/M.C./P.3
inertia of the rod about one end is 3  10-3
kg m2.)
A.
B.
C.
D.
15.
6.3
10
14
50
first-order
maximum
grating

incident
light
central
maximum
first-order
maximum
12. Due to air resistance, changes may occur
to a satellite orbiting the earth (assuming
nearly circular orbit). Which of the
changes below is incorrect?
When a certain monochromatic light is
passed through a diffraction grating, a
pattern of maxima and minima is observed
as shown.
Which of the following
combinations would produce the largest
angle  between the first-order maxima?
A. The total mechanical energy of the
satellite will decrease.
B. The angular momentum of the
satellite about the earth’s center will
decrease.
C. The linear speed of the satellite will
increase.
D. The time needed for the satellite to
complete one revolution will increase.
A.
B.
C.
D.
Grating
(lines per mm)
200
200
400
400
Colour of
light used
blue
red
blue
red
13.
16.
Q
L1
L2
time
P
The waveforms in the figure show the time
variation of two physical quantities P and
Q. What is the phase relationship between
P and Q?

.
2

B. P leads Q by .
4

C. Q leads P by .
2

D. Q leads P by .
4
A. P leads Q by
14. In which of the following the phenomenon
of polarization cannot be observed?
A. Light reflected from the surface of
water.
B. Microwaves
emitted
from
a
transmitter.
C. Light scattered from a clear sky.
D. Ultrasonic waves used in sonar.
20 cm
In the figure, L1 and L2 are two thin lenses
with the same focal length 40 cm placed
coaxially 20 cm apart. A beam of light
originating from a distant object is
incident on L1. Which of the following
statements about the final image formed
by the system of lenses is correct?
A. It is real and formed on the right of
L2.
B. It is real and formed between L1 and
L2.
C. It is virtual and formed between L1
and L2.
D. It is virtual and formed on the left of
L1.
17. A stretched string is 1 m long and is fixed
at both ends. Stationary waves of 400 Hz
and 450 Hz but no other intermediate
frequency can be formed. What is the
02 AL Physics/M.C./P.4
speed of the mechanical waves along the
string?
20.
X
A.
B.
C.
D.
25 ms-1
50 ms-1
100 ms-1
200 ms-1
Y
18. When a source emitting sound waves of a
fixed frequency moves towards a
stationary observer in air, the pitch of the
sound heard by the observer is different
from that when the source is at rest. This
is due to a change in the
In the above figure the solid lines
represent part of an electric field due to a
fixed point charge Q (not shown in the
figure). A charge particle q, subjected
only to electric force in the field, travels
along the dotted curve shown. Which of
the following conclusions can be drawn?
(1) number of waves emitted per second
from the source.
(2) speed of sound in air.
(3) wavelength of sound in air.
A.
B.
C.
D.
A. q is traveling from X to Y.
B. The charge of q has the same sign as
that of Q.
C. q has a greater speed at X than at Y.
D. The electric potential at X due to Q is
higher than that at Y.
(1) only
(3) only
(1) and (2) only
(2) and (3) only
19. The spectra produced by element X, one
on earth and the other on a distant star, are
compared.
21.
Spectrum form element X on earth:
Red
Green Violet
Spectrum from element X on the distant
star:
What is the most probable reason for the
difference in the spectra readings?
A.
B.
C.
D.
The universe is expanding.
The star is approaching the earth.
The star is receding from the earth.
The star is spinning about its axis.
The above figure shows an electron
entering a uniform field which may be
electric or magnetic.
Which of the
following
descriptions
about
the
subsequent motion of the electron is
correct?
A. Only in a magnetic field can the
electron be deflected by more than
90.
B. Only in an electric field does the force
depend on the magnitude of the
charge on the electron.
C. Whether the field is electric or
magnetic, the speed of the electron
will increase.
D. Whether the field is electric or
magnetic, the magnitude and direction
of the force acting on the electron are
constant.
02 AL Physics/M.C./P.5
22.
X
Y
Three identical capacitors, each of
capacitance C, form a network as shown.
What is the equivalent capacitance
between terminals X and Y?
A. C
3
B.
C
2
2
C.
C
3
D. 3C
In the above circuit, the d.c. supply has an
e.m.f. of 9 V and its internal resistance is
negligible.
V1, V2 and V3 are three
voltmeters with the same finite internal
resistance. If V1 reads 4 V, find the
reading of V3 and the potential difference
across resistor R.
A.
B.
C.
D.
Voltmeter reading
Potential
of V3
difference across R
3V
1V
5V
1V
1V
5V
1V
3V
25. A d.c. supply of constant e.m.f. and
internal resistance is connected to a
variable resistor of resistance R. Which of
the following graphs best shows how the
total power P delivered by the supply
varies with R?
23.
A.
P
A parallel-plate capacitor is first charged
by connecting it to a battery. After
disconnecting the battery, one of the plates
of the capacitor is shifted upward slightly
as shown. What would happen to each of
the following quantities?
0
B.
P
V: the potential difference between the
plates
Q: the magnitude of the charge on each
plate
C: the capacitance of the capacitor
A.
B.
C.
D.
V
decreased
unchanged
increased
increased
Q
unchanged
decreased
decreased
unchanged
C
increased
decreased
decreased
decreased
R
0
R
C.
P
24.
0
9V
R
S
V3
V1
V2
R
02 AL Physics/M.C./P.6
D.
A circular frame and a square frame, made
from the same type of insulated metal
wires, are placed in a uniform magnetic
field as shown. When the flux density of
the field is increased at a steady rate, the
ratio of the induced current in the circular
frame to that in the square frame is
P
R
0
A.
B.
C.
D.
26. A capacitor is discharged through a
resistance of 1 k. If the time constant of
the discharging circuit is 2 ms, what is the
capacitance of the capacitor?
A.
B.
C.
D.
1:1
1:
:4
2:
29.
0.5 F
1 F
2 F
5 F
P
Q
27.
P
Q
60
l
R
v
S
A metal rod of length l is inclined at 60 to
rail PQ as shown. It is moved across a
uniform magnetic field along the direction
of the two horizontal rails PQ and RS. If
the rod moves with a uniform velocity v
and the flux density of the field is B, the
e.m.f. induced in the rod is
Blv
.
2
B. Blv.
2Blv
C.
.
3
Three long straight parallel wires P, Q and
R carrying currents of the same magnitude
are situated at the vertices of an equilateral
triangle as shown. The currents in wires P
and R are directed out of the paper.
Which of the following indicates the
direction of the force acting on wire P?
→
↓
C. ↑
D. ↗
A.
B.
30. A steadily running motor draws a current
of 2 A from a battery of e.m.f. 5 V. The
internal resistance of the battery is
negligible. If the resistance of its armature
coil is 0.5 , estimate the efficiency of the
motor.
A.
D.
R
3Blv
.
2
A.
B.
C.
D.
28.
uniform
magnetic
field
60%
70%
80%
90%
02 AL Physics/M.C./P.7
31.
33.
I
Y1
E
Y2
In the circuit shown, the voltages across
the resistor and capacitor are respectively
fed to the input terminals Y1 and Y2 of a
dual trace CRO where E is the common
earth terminal. Which of the following
pairs of traces could be obtained? (The
trace of Y1 is represented by a solid curve
and the trace Y2 is represented by a dotted
one.)
V
Which of the following combinations of a
cell, an ideal diode and a resistor will give
the above I-V relationship, where I and V
are the applied current and voltage
respectively?
A.
A.
B.
B.
C.
C.
D.
D.
34. Which of the following is/are the
advantage(s) of using negative feedback in
an operational amplifier for voltage
amplification?
32. To produce an X-ray photon of energy 3.6
 10-15 J, the bombarding electrons in the
X-ray tube must be accelerated through a
potential difference of at least
(Given: electronic charge = 1.6  10-19 C)
A.
B.
C.
D.
11.3 kV.
22.5 kV.
28.8 kV.
57.6 kV.
(1) greater stability
(2) larger voltage gain
(3) no distortion of the output
A.
B.
C.
D.
(1) only
(3) only
(1) and (2) only
(2) and (3) only
02 AL Physics/M.C./P.8
35. A beam of red light falls on one electrode
of a photocell and electrons are emitted.
The red beam is then replaced by a blue
one that has the same intensity. Which of
the following physical quantities would
decrease as a result of this change?
A. The maximum kinetic energy of the
photoelectrons emitted
B. The energy of each photon striking
the electrode
C. The number of photons striking the
electrode per second
D. The magnitude of the potential
difference across the photocell
required to reduce the photo-electric
current to zero
36. In which of the following calculations is it
necessary to use the Planck constant?
(1) Finding the momentum of an electron
from its kinetic energy
(2) Finding the energy of a photon
emitted as a result of the transition of
an electron between two energy levels
in an atom
(3) Finding the maximum kinetic energy
of
photoelectrons
from
the
wavelength of incident radiation
A.
B.
C.
D.
(1) only
(3) only
(1) and (2) only
(2) and (3) only
37. A hydrogen atom absorbs a photon of
wavelength  such that the electron in the
ground state (energy level corresponding
to n = 1) is brought to an excited state
(energy level corresponding to n = 3).
What is the maximum wavelength of a
photon that can cause ionization of a
hydrogen atom in the ground state?
A.
B.
C.
D.
8
9
9
8
3
2
2
3
38.
P
B
A
0
T
The graph shows the relation between the
pressure P and the absolute temperature T
of a fixed mass of an ideal gas, which
changes from state A to state B along the
path AB.
Which of the following
statements is/are correct?
(1) The graph shows that P is directly
proportional to T.
(2) The volume V of the gas increases.
(3) All the points on straight line AB
PV
satisfy the relation
= constant.
T
A.
B.
C.
D.
(1) only
(3) only
(1) and (2) only
(2) and (3) only
39. What is the order of magnitude of the
number of molecules in 1 cm3 of air in an
atmospheric pressure of 105 Pa and at
room temperature?
(Given: Universal gas constant = 8.31 JK1
mol-1
Avogrado constant = 6.02  1023 mol-1)
A.
B.
C.
D.
1025
1019
1016
1013
40. At 80 C, the r.m.s. speed of the molecules
in a fixed mass of an ideal gas is c. If the
temperature is increased to 160 C, the
r.m.s. speed of the gas molecules would
become
A.
B.
C.
D.
2c.
1.4c.
1.2c.
1.1c.
02 AL Physics/M.C./P.9
41.
on a quiescent collector current of 3 mA
and with the base-emitter junction voltage
VBE = +0.6 V. What should be the value
of the base-bias resistor RB?
ln(A/Bq)
5
A.
B.
C.
D.
t/s
0
400
The graph above shows how the logarithm
of the activity A of a radioactive isotope
varies with time t. What is the half-life of
the isotope?
A.
B.
C.
D.
128 k
144 k
160 k
176 k
44.
50 k
10 k
P
V1
- 15 V
V2
42. Which of the following situations cannot
be explained by using Bernoulli’s
equation?
(1) An object falling with terminal
velocity in air
(2) The curved path described by a
spinning tennis ball
(3) The flow of water out of a tank
through a small hole near its bottom
A.
B.
C.
D.
(1) only
(3) only
(1) and (2) only
(2) and (3) only
V0
50 k
0V
The figure shows an operational amplifier
circuit. When V1 = +2.7 V and V0 = -0.9
V, what is the potential at P?
A.
B.
C.
D.
0V
0.6 V
2.1 V
2.4 V
45. The diameter of the bore of a capillary
tube can be determined by introducing a
small quantity of mercury into the
capillary. It is possible to measure the
length of the mercury thread to within 2%
and the mass of the mercury used to within
4%. Assuming negligible error in the
density of mercury, the percentage error in
the calculated diameter of the capillary
bore is at most
43.
+ 6V
RB
C
B
+15 V
10 k
200 s
55 s
24 s
0.42 s
A.
B.
C.
D.
E
0V
The figure shows a typical voltageamplifier circuit built from a transistor
with current gain 80. It operates normally
- End of Paper -
2%.
3%.
4%.
6%.
02 AL Physics/M.C./P.10
Question No.
Key
Question No.
Key
1.
2.
3.
4.
5.
D (17)
C (58)
B (55)
B (25)
A (66)
26.
27.
28.
29.
30.
C (88)
D (69)
A (18)
A (43)
C (88)
6.
7.
8.
9.
10.
D (43)
A (89)
C (20)
A (36)
C (75)
31.
32.
33.
34.
35.
C (38)
B (88)
C (30)
A (53)
C (51)
11.
12.
13.
14.
15.
B (43)
D (33)
A (51)
D (81)
D (52)
36.
37.
38.
39.
40.
B (30)
A (46)
D (23)
B (72)
D (48)
16.
17.
18.
19.
20.
A (26)
C (40)
B (69)
D (33)
C (25)
41.
42.
43.
44.
45.
B (75)
A (66)
B (70)
C (52)
B (37)
21.
22.
23.
24.
25.
A (31)
B (91)
D (61)
D (29)
C (34)