TRIAL SEM 2 SMJK CHUNG HWA CONFUCIAN PULAU PINANG 2022

SMJK CHUNG HWA CONFUCIAN PULAU PINANG
STPM TRIAL EXAMINATION (2022)
PHYSICS PAPER 2 (UPPER SIX)
1 ½ HOURS

Prepared by : Chan Phaik Ying
Checked by : Pn. Phang Li Lee
Approved by :

Instructions to candidates: Approved by : En. Chew YoonSeng

DO NOT OPEN THIS QUESTION PAPER UNTIL YOU ARE TOLD TO DO SO.

This paper consists of 12 printed pages.

Answer all questions in Section A. Marks will not be deducted for wrong answers. For each question, four

suggested answers are given. Choose the correct answer and shade the answer in the answer sheet given.

Answer all questions in Section B. Write your answers in the spaces provided.

Answer any two questions in Section C. All essential working should be shown. For numerical answers, unit

should be quoted wherever appropriate. Begin each answer on a fresh sheet of paper and arrange your answer

in numerical order.

Tear off the cover page and answer sheet of Section B (Page 8 and 9), and tie them together with your answer

sheets of Section C.

NAME : ______________________________ CLASS : _________________

Section A

Section B
16
17

Section C

Total

Answers: Section A (15 marks) 11.
1. 12.
6. 13.
2. 7. 14.
8. 15.
3. 9.
10.
4.

5.

2

Section A (15 marks)

Answer all questions in this section.

1. Which one of the following staements is true about an electric field at a point?
A It indicates the total force on a point charge at that point.
B It indicates the electric force per unit mass on a point charge at that point.
C It indicates the electric force per unit charge on a point charge at that point.
D It indicates the electric charge per unit mass on a point charge at that point.

2. Suppose A and B are two points near an infinitely large charged plate. If the amount of
work required to move +15 C of charge a distance of 20 cm, from point A to point B is
6.0 J, which of the following statements are true?
I. The charge experiences same magnitude of force at A and B.

II. Point A has an electric potential 0.40 V greater than that of point B.

III. If point A is closer to the charged plate, the plate is positively charged.
IV. The electric field strength along line AB is 2.0 N C-1 pointing from B to A.

A I and IV B II and III C I, II and III D All of the above

3. Two capacitors C1 and C2 of capacitance 1.0 µF and 0.5 µF are connected in series to a

100 V source. What is the ratio of the energy stored in C1 to that in C2?

A2 B 0.5 C 0.25 D4

4. A dielectric is inserted into an air-filled parallel plate capacitor of capacitance 1000 pF
"
so that # of the space between the plates is filled as shown in Figure 1.

Dielectric

Positively charged plate Negatively charged plate

Figure 1

If the dielectric constant is 9.0, what is the new capacitance of the capacitor?

A 400 pF B 700 pF C 3700 pF D 6300 pF

5. Current flows in a metallic conductor when a potential difference is applied across it.
Which of the following statements is true?
A Potential energy of charge carrier decreases as it moves.
B The total energy of the charge carrier increases as it moves.

C The charge carriers accelerate to the region of lower potential.
D The electric field is pointing into the direction opposite to that of flow of current.

3

6.

Figure 2

Figure 2 shows a segment of a current carrying conductor. If a steady current flows
through the conductor, how does drift velocity vd vary with position x?

A vd C vd

0 x0 x
B vd D vd

0x 0x

7. A power supply of negligible resistance is connected to a lamp. Which of the following
circuits could not be used to vary the voltage across the lamp ?
ABCD

8. A standard cell with an e.m.f. 1.30 V is used in a potentiometer circuit to determine the
potential difference across a potentiometer wire AB. The galvanometer gives a zero

reading when the jockey touches position C with length AC = l1 and BC = l2.

A l1 C B
Standard cell, 1.30 V l2

Figure 3

The potential difference across AB is
" C $ "'( 1.30 V
A $ " + '( 1.30 V

B $ "'( 1.30 V D $ " + '( 1.30 V
"

4

9. Which is not true about the multiplier to convert a galvanometer into a large scale
voltmeter?
A The multiplier has high resistance.
B The multiplier has the same current as the galvanometer.

C The multiplier is connected in parallel with the galvanometer.
D The multiplier increases the potential difference of the system at the same total

current.

10. The Hall voltage in a sample is 5.0 mV when the current through the sample is I and the sample
is in a magnetic flux density B applied perpendicularly to its plane. When the current is changed
"
to 2I and the magnetic flux density is reduced to / , the Hall voltage is now

A 0.50 mV B 2.0 mV C 13 mV D 50 mV

11. A current I flows through a loop. The direction of the current and the shape of the loop
are as shown in figure 4.

Figure 4

If MA = R, MB = 2R and CM perpendicular to BM, the magnetic flux density at the

center of the loop is

A 5 çæ µ0I ö÷ and out of the plane of the paper
16 è R ø

B 5 çæ µ0I ö÷ and into the plane of the paper
16 è R ø

C 7 çæ µ0I ö÷ and out of the plane of the paper
16 è R ø

D 7 çæ µ0I ö÷ and into the plane of the paper
16 è R ø

5

12. A square coil has n turns and sides of length l carries a current I in the uniform magnetic
field of field strength B between the poles of magnets.

Figure 5
Which of the following diagrams shows the correct direction and magnitude of the
catapult force as viewed from above?
AC

BD

13. Figure 6 shows two coils P and Q with the same axis. Switch S is then closed and a
current flows through coil P as shown in the figure.

Figure 6
Which of the following steps will produce an induced current in coil Q that flows in
the same direction as the current in coil P.
A Switch S is opened.
B Coil Q is moved towards coil P.
C The resistance of the rheostat is decreased continuously.
D Coil P shrinks gradually to reduce the diameter.

6

14. A steady current I produces power P in a resistor. When an alternating current flows in

the resistor, the average power produced is 2P. What is the peak value of the alternating

current?
A I B
C √2 D 2

2

15. Which of the following relates correctly the dependence of the reactance of a capacitor,

and that of an inductor to the frequency f of the alternating current?

Capacitor Inductor

A constant directly proportional to f

B inversely proportional to f constant

C inversely proportional to f directly proportional to f

D directly proportional to f inversely proportional to f

7

Section B (15 marks)

Answer all questions in this section.

16. (a) Define electric field strength. [1 mark]

_____________________________________________________________________

_____________________________________________________________________

(b) Two parallel metal plates are places horizontally as shown in Figure 7. The lower plate

is earthed and the upper plate is connected to a 1.9 kV supply. The separation between
the plates is 14 mm. A charged sphere, S is placed to float in between the plates.

Figure 7 [2 marks]
i) Determine the electric field strength in between the plates.

ii) If the mass of sphere S is 10 g, determine the magnitude and sign of the charge in

the sphere? [3 marks]

iii) If the plates are moved closer, explain how the electric field changes. What would

happen to sphere S? [2 marks]

__________________________________________________________________

__________________________________________________________________

__________________________________________________________________

8

17. a) State Kirchhoff’s laws. [2 marks]

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

a) Determine I1, I2, I3 and potential difference between b and f . [5 marks]

Figure 8

9

Section C [30 marks]

Answer any two questions in this section.

18. a) Define capacitance of a parallel plate capacitor. [1 mark]

b) Three capacitors, each of capacitance 48 µF, are connected as shown in figure 9. The
maximum safe potential difference that can be applied across each capacitor is 6.0 V.

C1

C3

C2

Figure 9 [2 marks]

i) Calculate the effective capacitance across AB. [5 marks]
ii) Calculate the maximum voltage across AB. [3 marks]
iii) Determine the charges in each capacitor at maximum voltage.

c) i) Define time constant for a discharging of a capacitor. [1 mark]
ii)
After the capacitors in Figure 9 are fully charged to maximum voltage, terminals A

and B are then connected to a 55 kW resistor. Determine the time taken for the

voltage to halve in the capacitors. [3 marks]

19. a) State Faraday’s law and Lenz’s law. [2 marks]

b) A 215 turns planar coil with a surface area of 25.0 cm2 is placed in a uniform magnetic

field B of 2.05 T. Initially, the plane of the coil is perpendicular to the field. The coil is

then rotated about an axis perpendicular to the magnetic field with a period of 0.16 s.

i) Determine the initial magnetic flux linkage through the coil. [2 marks]

ii) Derive the induced e.m.f. in the coil at time t. [5 marks]

c) A long solenoid has N1 turns, length L and cross-sectional area A. A short coil with N2

turns is wound around the middle of the long solenoid.

i) Explain the phenomenon of mutual induction. [1 marks]

ii) Derive an expression for mutual inductance in terms of A, N1, N2 and L. [3 marks]

iii) If the length of the primary coil in increased without changing the number of turns

of the coils, explain what happens to induced e.m.f. in the secondary coil when an

a.c. source is connected across the primary coil. [2 marks]

10

20. Figure 10 shows an alternating voltage of V = 198 cos 100pt, where V is in volts and t is in

seconds, connected to a resistor of resistance R = 1.5 W, and an inductor of inductance L =
6.3 mH, in series.

Figure 10

a) Define r.m.s. voltage. [1 mark]

b) Determine

i) the r.m.s. voltage of the voltage, [2 marks]

ii) the impedance of the circuit, [3 marks]

iii) the r.m.s. potential difference across the inductor, and [2 marks]

iv) the phase difference between the current in the circuit and the supplied voltage.

[2 marks]

c) Sketch the phasor diagram of the circuit. [2 marks]

d) Calculate the peak current value and express current in the circuit in terms of t.
[3 marks]

11

12

STPM 2022 Trial Exam
Physics Paper 2

Answer scheme

Section A (15 marks) 6C 11 D
7B 12 A
1C 8D 13 A
2A 9C 14 D
3B 10 B 15 C
4C
5A

Section B (15 marks)

16. a) Force per unit positive charge at a point. [1]

b) i)

= [1]

= 1.9 × 10* = 1.4 × 10- ,0 [1]
14 × 10,*

ii)
[ 1 ] = [1]

= = 0.010 × 9.81
1.4 × 10-
= 0.70 [1]

iii) Electric field strength increases because ∝ 90. [1]
Sphere S accelerates/moves upwards. [1]

17. a) Kirchhoff’s first law states that the algebraic sum of the current entering any junction must be zero.

: = 0 [1]

Kirchhoff’s second law states that the algebraic sum of the products of current and resistance equals
the algebraic sum of e.m.f. in a closed loop.

: = : [1]

b) 0 + > − * = 0 [1]

14.0 + 10.0 = −4.0 > + 6.0 0, 10.0 = 6.0 0 + 2.0 * , 14.0 = −4.0 > − 2.0 * any 2 ----------[2]

0 = 2.00 A, [1]
> = -3.00 A,
* = -1.00 A

BC = C − B [1]
= +10.0 − 6.0 0
= −2.0 V ( B > C)

Section C (30 marks)

18. a) The ratio of the charge, Q on each plate to the potential difference between the plates. [1]

b) i) 1 1 1
FG + *
= 0 > + [1]

= 96 1 + 48 1
× 10,H × 10,H

Ceq = 32 µF [1]

ii) ∝ 0 OR ∝
I

* = 0> [ 1 ] * = * [1]
0 KL > * 0 KL > 0 KL > [1]

* = 2 0 KL > [ 1 ] * = 2 0 KL >

V3 = 6.0 V [1]
V1 = V2 = 3.0 V [1]

VAB = 9.0 V [1]

iii) Q = CV [1]

Q1 = Q2 = 48 ´ 10-6 ´ 3.0 = 140 µC [1]

Q3 = 48 ´ 10-6 ´ 6.0 = 290 µC [1]

c) i) Time taken for the charge/current/voltage to decay to 0 of its initial value. [1]
F
ii) t = RCeq [1]

= MN ,QP [1]

,SR = 0 t = 1.2 s [1]
>

19. a) Faraday’s law states that the e.m.f. induced in a conductor is directly proportional to the rate of
change of magnetic flux linked with the conductor. [1]
Lenz’s law states that the direction of induced current is such that the magnetic field produced will
oppose the change that induces the current. [1]

b) i) ΦU = [1] = 215 × 2.05 × 25.0 × 10,[
= 1.10 Wb [1]

ii) = >] = 39 rad s,0 [1]
^
at time t, = cos [1]
9i
e.m.f. induced, = − 9P [1]

= sin [1]
= 43.2 sin 39.3 V [1]

c) i) e.m.f. is induced in a conductor when the current in a neighbouring conductor changes. [1]

ii) = U = mnop q [1]
r

Φ = > = mn op os qM [1]
r

Φ = → = mnop os M [1]
r

iii) The mutual inductance decreases. [1]
e.m.f. induced decreases. [1]

20. a) The value of d.c. voltage that dissipates heat at the same rate as the mean power dissipated when the
a.c. flows in the resistor. [1]

b) i) Lvw = x [1]
√>

= 0z{ = 140 V [1]
√>

ii) r = [1]
= • > + ( )> [1]

= •1.5> + (100 × 6.3 × 10,*)> = 2.5 Ω [1]

iii) x„ = …„ [1]
x = †
100 × 6.3 × 10,*
r 2.5 × 140 = 110 V [1]

iv) tan = …„ [1]
‰
100 × 6.3 × 10,*
= tan,0 1.5 = 53°
[1]

c) - VL leads VR by 90°. [1]
VL V - Correct V and angle labelled. [1]

53°
VR

d) v‹Œ = x•Ž• [1]
†
0z{
= >.- = 79 A [1]

I = 79 cos (100p - 0.93) [1]