Download 99mc

99 AL Physics/M.C./P.1
1999 Hong Kong Advanced Level Examination
AL Physics
Multiple Choice Question
1.
3.
A
B
F
Two objects A and B of equal mass m are
connected by two identical light springs
and are placed on a horizontal smooth
surface. A horizontal force F is applied to
B so that the system is in equilibrium. If
the applied force F is suddenly removed,
what are the magnitudes of the
acceleration of each object at the instant
when force F is removed?
A.
B.
C.
D.
E.
The above figure shows an open wagon
moving with negligible resistance in
vertically falling rain. An appreciable
amount of rain falls into the wagon and
accumulates there. What are the effects of
the accumulating rain on the speed,
momentum and kinetic energy of the
wagon?
(Ignore the effects of the
raindrops hitting the front of the wagon.)
Acceleration of A Acceleration of B
F
zero
m
zero
zero
F
F
m
2m
F
zero
m
F
F
m
m
A.
B.
C.
D.
E.
4.
2.
30 cm
40 cm
F
horizontal
surface
A block of mass 5 kg is placed on the
inclined surface of the wedge shown
above. All contact surfaces are assumed
to be smooth. What is the magnitude of
the horizontal force F exerted on the
wedge so that it remains stationary while
the block is sliding down the inclined
surface with acceleration?
A.
B.
C.
D.
E.
0N
18 N
24 N
30 N
32 N
speed momentum kinetic energy
decreased unchanged
decreased
decreased unchanged
unchanged
decreased decreased
decreased
unchanged unchanged
unchanged
unchanged increased
increased
The velocity of an object changes with
time but the magnitude of its acceleration
remains unchanged. The motion of the
object can be
(1) simple harmonic motion.
(2) parabolic motion of a projectile.
(3) uniform circular motion.
A.
B.
C.
D.
E.
(1) only
(3) only
(1) and (2) only
(2) and (3) only
(1), (2) and (3)
99 AL Physics/M.C./P.2
5.
7.
E/J
/Nm
10
1
0
v2/m2s-2
1
0
The above graph shows the variation of
kinetic energy E with the square of
velocity v of a moving mass m. What is
the momentum of the mass when it is
moving at a speed of 2 ms-1?
A.
B.
C.
D.
E.
14
20
t/s
A turntable of moment of inertia 1.0  10-3
kg m2 is under the action of a torque. The
variation of the torque  acting about the
axis of rotation with time t is as shown. If
the turntable is at rest initially, what is its
angular momentum at t = 20 s?
1 Ns
2 Ns
4 Ns
8 Ns
16 Ns
A.
B.
C.
D.
E.
40 kg m2 s-1
100 kg m2 s-1
200 kg m2 s-1
1  105 kg m2 s-1
2  105 kg m2 s-1
6.
2m
8.
Q
m
P
A light, rigid rod of length 1 m is hinged
smoothly at P at one end. Two small
masses m and 2m are fixed to the midpoint and the other end of the rod
respectively. The rod is held vertically
above P and is released from rest. What is
the total rotational energy of the system
when the rod rotates to the position
vertically below P?
(Neglect air
resistance)
A.
B.
C.
D.
E.
2.5 mg
4.5 mg
5 mg
7.5 mg
9 mg
P
v
A small ball-bearing is projected with
velocity v from the lowest position P of a
vertical circular track which is not smooth.
The ball-bearing starts to leave the track at
Q. Which of the following diagrams best
represents all the forces acting on the ballbearing at Q?
A.
Q
P
B.
Q
P
C.
Q
P
99 AL Physics/M.C./P.3
C.
U
D.
Q
0
x
P
E.
D.
Q
U
P
0
x
9.
E.
a
U
0
x
The above graph shows the variation of
the acceleration a of a particle with its
displacement x from a fixed point. Which
of the following graphs shows the
variation of its potential energy U with x?
0
x
10.
A.
U
0
x
B.
U
0
x
A converging light beam is directed
towards a convex mirror M. The reflected
beam then passes through a convex lens L
and forms an image at I. Which of the
following about the focal lengths of M and
L is correct?
A.
B.
C.
D.
E.
focal length of M
more than 4 cm
less than 4 cm
4 cm
less than 4 cm
more than 4 cm
focal length of L
2 cm
2 cm
2 cm
4 cm
4 cm
99 AL Physics/M.C./P.4
11. An astronomical refracting telescope is
adjusted to view a distant object under
normal adjustment.
Which of the
following statement is/are correct?
(1) The first image formed by the
objective is real and is smaller than
the object.
(2) The final image formed by the
eyepiece is at the least distance of
distinct vision from the eye.
(3) If part of the objective is blocked by
an opaque obstacle, part of the final
image could not be viewed.
A.
B.
C.
D.
E.
(1) only
(3) only
(1) and (2) only
(2) and (3) only
(1), (2) and (3)
12. In a Young’s double slit experiment, a
monochromatic light source of wavelength
700 nm is used and the separation of the
slits is 0.1 mm. If 15 bright fringes are
observed, what is the angle subtended by
those fringes at the centre of the double
slit?
15 bright fringes
angle subtended
at the centre of
the double slit
A.
B.
C.
D.
E.
4.8
5.2
5.6
6.0
6.4
13. Two dippers S1 and S2 1.2 cm apart are
attached to a vibrator. They vibrate in
phase in a ripple tank and generate waves
of wavelength 0.8 cm.
S1
S2
1.2 cm
Which of the following statements is/are
correct?
(1) S1 and S2 are positions of antinodes.
(2) There is only one point between S1
and S2 which is always stationary.
(3) The separation between two nearest
antinodes between S1 and S2 is 0.4 cm.
A.
B.
C.
D.
E.
(1) only
(3) only
(1) and (2) only
(2) and (3) only
(1), (2) and (3)
14. On a straight road, a car and an ambulance
move with uniform speeds u1 and u2
respectively (with u2 > u1) in the same
direction.
Initially the ambulance is
behind the car and it overtakes the car
after some time.
The siren on the
ambulance continuously emits a sound of a
certain frequency. What is the ratio of the
wavelength of sound received by an
observer in the car before the ambulance
overtakes to that after the ambulance
overtakes?
(Given: velocity of sound in air = v)
A.
v  u2
v  u2
B.
v  u2
v  u2
C.
u2  u1
u2  u1
D.
v  u2  u1
v  u2  u1
E.
v  u2  u1
v  u2  u1
99 AL Physics/M.C./P.5
15. Students A and B are standing 5 m apart.
A shouts to B and the intensity level in db
recorded by B is x. A then walks away
from B so that they are 10 m apart. If A
shouts again with the same power, what is
the intensity level in db recorded by B?
A.
B.
1
x
4
1
x
2
(3) If the resistor with resistance R1 is
removed, the resulting equivalent
resistance is increased.
A.
B.
C.
D.
E.
18. Which of the following statements about a
communication satellite in parking orbit
above the earth’s surface is incorrect?
x
C. log10
4
D. x - 3
E. x - 6
A. It is accelerating towards the centre of
the earth at all times.
B. It must be in a circular orbit above the
earth’s equator.
C. It is always vertically above the same
place on the earth’s surface.
D. It must be rotating in the same sense
and with the same angular speed as
the earth.
E. It is at a height where its gravitational
potential energy is numerically equal
to its kinetic energy.
16.
A
V
R
The above circuit can be used to find the
resistance of the resistor R. Which of the
following statements is/are correct?
(1) The current passing through the
ammeter is in fact larger than that
passing through R.
(2) The ratio of voltmeter reading to
ammeter reading is in fact smaller
than the resistance of R.
(3) The circuit is suitable for measuring
high resistance.
A.
B.
C.
D.
E.
(1) only
(3) only
(1) and (2) only
(2) and (3) only
(1), (2) and (3)
(1) only
(3) only
(1) and (2) only
(2) and (3) only
(1), (2) and (3)
17. Three resistors of resistance R1, R2 and R3
are connected in parallel. It is known that
R1 > R2 > R3. The equivalent resistance of
this combination is R. Which of the
following statements is/are correct?
(1) Energy dissipated in moving 1 C of
charge through the resistor of
resistance R1 is greater than that
through R3.
(2) R is smaller than R2.
19.
R1
P
R3
R2
Q
S
In the above circuit, the battery has
constant e.m.f. and negligible internal
resistance. If switch S is closed, what
would happen to the electric potential at P
and at Q?
A.
B.
C.
D.
E.
Potential at P
increased
increased
unchanged
decreased
decreased
Potential at Q
increased
decreased
unchanged
increased
decreased
99 AL Physics/M.C./P.6
20. Each of the following three students states
a conclusion after learning the formulae P
= IV, P = V2/R and P = I2R in electricity.
Which of these conclusion is/are correct?
(1) The power dissipated by any electric
appliance can be calculated from P =
IV.
(2) The power dissipated by a kettle is
inversely proportional to its resistance
as P = V2/R.
(3) The power consumed by a running
motor cannot be calculated from P =
I2R.
A.
B.
C.
D.
E.
(1) only
(3) only
(1) and (2) only
(2) and (3) only
(1), (2) and (3)
21. Which of the following statements about
electric field lines is incorrect?
A. They are closest where the field is
strongest.
B. They are always perpendicular to
equipotential lines.
C. They always point from high electric
potential to low electrical potential.
D. Work has to be done in moving an
electron along the direction of a field
line.
E. They tend to attract one another.
22. A charged capacitor of capacitance 47 F
is connected to a voltmeter. The voltmeter
reading drops from 8 V to 2 V in 7.8 s.
Find the resistance of the voltmeter.
A.
B.
C.
D.
E.
60 k
80 k
120 k
166 k
240 k
C. The conduction electrons in the wire
are accelerated momentarily in the
opposite direction to that of the
electric field.
D. The conduction electrons collide with
one another, giving out heat energy.
E. The current in the wire is proportional
to the average drift velocity of the
electrons.
24.
45 V
2 F
2 F
Output
8 F
0V
0V
Three capacitors are connected to a 45 V
supply as shown in the above circuit. The
voltage at the output is
A.
B.
C.
D.
E.
5V
15 V
30 V
36 V
40 V
25. A capacitor is charged by a constant
current. Which of the following graphs
shows the time variation of the energy
stored in the capacitor during the charging
process?
A.
energy
time
B.
energy
23. A resistance wire is connected across the
terminals of a battery. Which of the
following statements is incorrect?
A. Before connection to the battery, the
conduction electrons in the wire move
randomly.
B. After connection to the battery, an
electric field is set up along the length
of the wire.
time
C.
99 AL Physics/M.C./P.7
energy
B.
C.
time
D.
energy
D.
E.
time
E.
energy
time
27. Which of the following graphs correctly
shows the variation of the magnetic flux
density B along the axis of a long solenoid
carrying a steady current with its length l?
26.
S
E
C
R
A.
B
To
CRO
0
l
B.
B
In the above circuit, a capacitor C is
charged from a battery E and then
completely discharged through a resistor R
using a vibrating reed switch S. The
waveform displayed on the screen of the
CRO with suitable time base should be
0
l
C.
B
A.
0
l
99 AL Physics/M.C./P.8
D.
A.
B.
C.
D.
E.
B
0
(1) only
(3) only
(1) and (2) only
(2) and (3) only
(1), (2) and (3)
l
30.
E.
long
straight
wire
carrying 6 cm 6 cm
an a.c.
A
B
current
B
0
search coil
To CRO
l
(1) Boltzmann constant k times absolute
temperature T
(2) Planck constant h times frequency 
(3) Electronic charge e times potential
difference V
The figure shows a long straight wire
carrying an a.c. current which lies on the
plane of the paper. When a small search
coil is placed at B such that the plane of
the coil is on the paper, the length of the
trace on the CRO is 2 cm (with the time
base of the CRO switched off). If the
search coil is moved to A, the length of the
trace would be
A.
B.
C.
D.
E.
A.
B.
C.
D.
E.
28. Which of the following products is/are
measured in joules?
(1) only
(3) only
(1) and (2) only
(2) and (3) only
(1), (2) and (3)
29.
31. For which of the following does the force
between two objects vary inversely as the
square of the distance between their
centres?
S
2V
0.5 cm.
1 cm.
2 cm.
4 cm.
8 cm.
L
B
neon lamp
In the above circuit, a coil L of large
inductance, a 2 V light bulb B, a switch S
and a 2 V battery are connected in series.
A neon lamp is connected across L.
Which of the following statements is/are
correct upon the opening of switch S?
(1) A large e.m.f. is induced across coil L.
(2) The neon lamp lights up momentarily.
(3) Light bulb B continues to light up
until the neon lamp dies out.
(1) Two equal masses joined by a rubber
band under tension.
(2) Two long straight parallel conducting
wires carrying steady electric
currents.
(3) The earth and a satellite in its orbit.
A.
B.
C.
D.
E.
(1) only
(3) only
(1) and (2) only
(2) and (3) only
(1), (2) and (3)
99 AL Physics/M.C./P.9
32.
C. ultra-violet
D. visible light
E. X-rays
L
R
The above figure shows an a.c. circuit in
which a variable resistor R is connected in
series with an air-cored inductor L of
negligible resistance. The a.c. supply has
constant r.m.s. voltage and its frequency
can be varied. Which of the following
methods, on its own, can increase the
r.m.s. voltage across the variable resistor
R?
(1) Inserting an iron core in the inductor
L.
(2) Increasing the frequency of the a.c.
supply.
(3) Increasing the resistance of R.
A.
B.
C.
D.
E.
(1) only
(3) only
(1) and (2) only
(2) and (3) only
(1), (2) and (3)
33. The following are energy values for
hydrogen.
X
Y
Z
mean kinetic energy of hydrogen gas
molecules at room temperature
ionization energy of a hydrogen
atom
photon energy of a particular line in
the visible emission spectrum of
hydrogen
Which of the following shows the correct
ascending order (the least first) of these
energy values?
A.
B.
C.
D.
E.
X<Z<Y
X<Y<Z
Y<Z<X
Z<Y<X
Z<X<Y
34. When an electron in an atom falls from an
excited state to the ground state, which of
the following forms of radiation is not
emitted?
A. infra-red
B. gamma-ray
35.
A
B
P
Q
C
Two long, straight, parallel conducting
wires P and Q are positioned as shown.
The same current flows through both wires
and is directed into the plane of the paper.
Points A, B and C on the plane of the
paper are equidistant from both wires
where C is the mid-point between the
wires. Which of the following statements
is/are correct?
(1) The magnetic field strength at C is
greater than that at A.
(2) The directions of the magnetic field at
A and at B are the same.
(3) The magnetic field strength at B will
increase if the current flowing in the
wires increases.
A.
B.
C.
D.
E.
(1) only
(3) only
(1) and (2) only
(2) and (3) only
(1), (2) and (3)
36. A coil of metal wire is placed on a plane
perpendicular to a uniform magnetic field.
The coil is rotated through 180º about a
diameter as shown.
180
The total charge circulated in the coil due
to the induced current is independent of
A. the area of the coil.
B. the flux density of the magnetic field.
99 AL Physics/M.C./P.10
C. the number of turns of the coil.
D. the resistance of the coil.
E. the time taken for the flux change.
39.
p/kPa
B
A
37.
C
Y
T/K
0
A fixed mass of an ideal gas undergoes the
process ABC as shown in the pressuretemperature diagram.
Which of the
following deductions from the diagram is
incorrect?
X
S
V
4V
Two metallic containers X and Y of
volume V and 4V respectively are
connected by a narrow tube as shown.
Initially the tap S is closed and an ideal
gas is contained in X at a pressure of 400
kPa while container Y is evacuated. The
tap S is then opened and when equilibrium
is finally reached
A. the gas pressure in X is 100 kPa.
B. there are still gas molecules moving
through the tap S.
C. the product of pressure and volume of
the gas in X is equal to that in Y.
D. the density of gas molecules in X is
greater than that in Y.
E. the gas molecules in Y on average
move faster than those in X.
A. The volume of the gas at C is greater
than that at B.
B. No work is done by the gas when it
changes from A to B.
C. Work is done by the gas on the
surroundings when it changes from B
to C.
D. Heat energy is transferred to the gas
when it changes from A to B.
E. Heat energy is extracted from the gas
when it changes from B to C.
40.
K
38. Which of the following descriptions about
ideal gas is/are correct?
(1) An ideal gas obeys Boyle’s law only
under high temperature and low
pressure.
(2) The molecules of an ideal gas have no
size.
(3) The internal energy of an ideal gas
consists of kinetic energy only.
0
The above graph shows the variation in
maximum
kinetic
energy
K
of
photoelectrons with the frequency f of the
incident radiation on a metallic surface. If
radiation of twice the intensity is used,
which of the following graphs (dotted line)
shows the variation of K with f?
A.
A.
B.
C.
D.
E.
f
(1) only
(3) only
(1) and (2) only
(2) and (3) only
(1), (2) and (3)
K
0
B.
f
K
0
f
99 AL Physics/M.C./P.11
A.
C.
K
0
D.
f
B.
K
C.
0
E.
f
K
D.
0
f
E.
41. Three sinusoidal signals V1, V2 and V3 are
applied in pairs to the X- and Y- inputs of
a CRO and the resulting Lissajous figures
are as shown.
X-input
Y-input
Lissajous figures
42.
N
V1
V2
100
V2
V3
0
If V1 and V3 are applied to the X- and Yinputs respectively, the Lissajous figure
should look like
100
Z
For stable nuclides, the number of
neutrons N when plotted against the
number of protons Z would give points
lying within the above shaded region.
Which of the following statements is/are
correct?
(1) The heavy stable nuclides have more
neutrons than protons.
(2) Unstable nuclides decay to produce
new nuclides closer to the shaded
region.
99 AL Physics/M.C./P.12
(3) Unstable nuclides above the shaded
region usually decay through emission.
A.
B.
C.
D.
E.
(1) only
(3) only
(1) and (2) only
(2) and (3) only
(1), (2) and (3)
43. Carbon-14 is radioactive and undergoes decay with a half-life of about 5 600 years.
A GM-tube together with a scaler are used
in an experiment to determine the
concentration of carbon-14 in a piece of
excavated wood. To find an accurate
value for the activity of the excavated
wood, the experimenter should
(1) prepare a sample of pure carbon-14
from the piece of excavated wood.
(2) take a count over as long a period of
times as possible.
(3) take a second count without the
presence of the excavated wood.
A.
B.
C.
D.
E.
(1) only
(3) only
(1) and (2) only
(2) and (3) only
(1), (2) and (3)
44. Which of the following are reasonable
estimates of the density and volume of an
adult human?
A.
B.
C.
D.
E.
Density/kgm-3
100
100
1 000
1 000
10 000
Volume/m3
1
0.1
0.1
0.01
0.01
45. Which of the following will give rise to a
systematic
error
in
experimental
measurement?
(1) using a slow-running stop watch in
keeping time
(2) ignoring the background counts in
radioactive decay measurements
(3) uncertainty in locating the sharpest
image position in an optics
experiment
A. (1) only
B.
C.
D.
E.
(3) only
(1) and (2) only
(2) and (3) only
(1), (2) and (3)
99 AL Physics/M.C./P.13
Question No.
Key
Question No.
Key
1.
2.
3.
4.
5.
A
C
A
D
C
26.
27.
28.
29.
30.
A
B
E
C
D
6.
7.
8.
9.
10.
C
B
A
E
A
31.
32.
33.
34.
35.
B
B
A
B
D
11.
12.
13.
14.
15.
A
C
B
A
E
36.
37.
38.
39.
40.
16.
17.
18.
19.
20.
C
D
E
E
E
41.
42.
43.
44.
45.
21.
22.
23.
24.
25.
E
C
D
B
B
This item was deleted
B
D
E
A
D
C
D
C
C