2013 J2 H2 Physics CT2 P1

JJC 2013 9646/JC2 CT2 P1/2013 [Turn Over
JURONG JUNIOR COLLEGE

2013 JC2 Common Test 2

Name Class 12S

PHYSICS
Higher 2

Structured Questions

Candidates answer on the Question Paper.
No additional materials are required.
9646/1

2 Jul 2013

1 hour 15 minutes

READ THESE INSTRUCTIONS FIRST

Do not open this booklet until you are told to do so.

Write your name and class in the space provided at the top of this
page.

Write in dark blue or black pen.
You may use a soft pencil for any diagrams, graphs or rough working.
Do not use highlighters, glue or correction fluid.

Section A
Answer every question.

Section B
Answer any two questions.

At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each
question or part question.
For
Examiners Use
1
2
3
4
Total

(This question paper consists of 17 printed pages)


2

Data
speed of light in free space, c = 3.00 10
8
m s
1

permeability of free space,
o
= 4t 10
7
H m
1

permittivity of free space, c
o
= 8.85 10
12
F m
1
= (1/(36t)) 10
9
F m
1

elementary charge, e = 1.60 10
19
C
the Planck constant, h = 6.63 10
34
J s
unified atomic mass constant, u = 1.66 10
27
kg
rest mass of electron, m
e
= 9.11 10
31
kg
rest mass of proton, m
p
= 1.67 10
27
kg
molar gas constant, R = 8.31 J K
1
mol
1

the Avogadro constant, N
A
= 6.02 10
23
mol
1

the Boltzmann constant, k = 1.38 10
23
J K
1

gravitational constant, G = 6.67 10
11
N m
2
kg
2

acceleration of free fall, g = 9.81 m s
2

Formulae
uniformly accelerated motion, s = ut +
1
2
at
2
v
2
= u
2
+ 2as
work done on/by a gas, W = p AV
hydrostatic pressure, p = gh
gravitational potential,
| =
Gm
r

displacement of particle in s.h.m., x = x
o
sin et
velocity of particle in s.h.m., v = v
o
cos et

v =
2 2
( )
o
x x e
mean kinetic energy of a molecule of an ideal
gas
E =
3
2
kT
resistors in series, R = R
1
+ R
2
+ . . .
resistors in parallel, 1/R = 1/R
1
+ 1/R
2
+ . . .
electric potential, V
=
o
Q
r t 4

alternating current / voltage, x = x
o
sin et
transmission coefficient, T exp(2kd)
where k =
2
2
8 ( ) m U E
h
t

radioactive decay x = x
o
exp(-t)
decay constant

=
1/ 2
0.693
t


3
Section A
Answer every question in this section.
1 In a nuclear fusion reaction, two light nuclei combine into a heavier nucleus with the release
of energy. The most basic fusion reaction is the fusion of two hydrogen nuclei
1
1
H.

There are two possible outcomes to such a fusion reaction. In reaction (1), a helium isotope
2
2
He is formed. In reaction (2), a hydrogen isotope
2
1
H and an unknown elementary particle
(X) are formed.

Reaction (1)
1 1 2
1 1 2
H H He +
Reaction (2)
1 1 2 a
1 1 1 b
H H H X + +

(a) Explain the term isotope.

[1]

(b) By reference to binding energy per nucleon, explain why energy is released in fusion
reactions.

[2]

(c)
State the values of a and b for the elementary particle
a
b
X .

a =
b = [1]


4
(d)
The hydrogen isotope
2
1
His readily found on Earth but not the helium isotope
2
2
He .
(i) Suggest a possible reason for this observation.

[1]

(ii) Hence deduce which reaction releases more energy.

[1]

(e) With the following information, show that the energy released in reaction (2) is
1.49 x 10
-13
J. [2]
Rest mass of
1
1
H = 1.007825 u
Rest mass of
2
1
H= 2.014102 u
Rest mass of X = 0.000549 u


5
Section B
Answer two questions from this section.
2 (a) When a stone drops into a pond, ripples of water waves propagate radially
outwards. Two particles on the surface of the pond perform simple harmonic motion
as the ripples pass them. The two particles are separated by 50.0 cm and in line
with the source.

A particular ripple takes 0.10 s to travel from the first particle to the second particle.
The particles are always in anti-phase.

(i) By reference to the displacement of the particles from the equilibrium
position, explain what is meant by the particles are always in anti-phase.

[2]

(ii) Calculate a possible speed of the water wave.

speed = m s
-1
[2]

(iii)
A third particle which is situated between them is
3
radians out of phase with
the first particle. Given that the wavelength of the water wave is 100.0 cm,
calculate the distance between the first particle and the third particle.

distance = m [2]


6
(b) Light of wavelength 590 nm is incident on a diffraction grating with
6.25 x 10
5
lines per metre. The screen is placed 10.0 cm away from the grating.
(i) Determine the total number of images produced by the light transmitted
through this grating.

number of images = [3]

(ii) Calculate the distance between the first-order maximum and the central
maximum on the screen.

distance = m [3]

(iii) Another diffraction grating of the same slit separation is placed in front of the
original grating such that their slits are perpendicular to one another as shown
in Fig. 2.1. A 2-dimensional pattern of bright spots is formed on the screen.

Fig. 2.1

Laser source
To Screen


7
Sketch the pattern obtained, showing clearly the relative separation of the
spots up to the 2
nd
order maxima. [2]

(c) Fig. 2.2 shows an arrangement used to determine the wavelength of
monochromatic light emitted by a laser.

Fig. 2.2

S
1
and S
2
are silts at right angles to the plane of this page. When the silts are
illuminated by light from the laser, they form coherent sources of light. An
interference pattern is formed on the screen from which measurements can be
taken to determine the wavelength.
(i) Explain what is meant by monochromatic.

[1]

Screen
Parallel
beam of
light from
laser


8
(ii) Describe how the concepts of diffraction and interference can be used to
explain the formation of the interference pattern.

[3]

(iii) If white light is used in the above experiment instead of monochromatic light,
state how the interference pattern would change.

[2]


9

3 A wire frame ABCD is supported on two knife-edges P and Q so that the section PBCQ on
the frame lies within a solenoid, as shown in Fig. 3.1. and Fig. 3.2.

Fig. 5.1

Electrical connections are made to the frame through the knife-edges so that the part
PBCQ of the frame and the solenoid can be connected in series with a battery. When
there is no current in the circuit, the frame is horizontal.

(a) When the frame is horizontal and a current passes through the frame and solenoid,
what can you say about the direction of the force, if any, due to the magnetic field of
the solenoid acting on

(i) side BC,

(ii) side PB?
[2]
Fig. 3.1
Fig. 3.2


10
(b) State two ways in which you could reverse the direction of the force on side BC.

1.

2.
[2]

(c) (i) The solenoid has 700 turns m
-1
and carries a current of 3.5 A. Given that the
magnetic flux density B on the axis of a long solenoid is
o
B ni = , where n is the number of turns per metre of the solenoid, and i is
the current in the solenoid,
calculate the magnetic flux density in the region of side BC of the frame.

magnetic flux density = T [1]

(ii) Side BC has length 5.0 cm.
Calculate the force acting on BC due to the magnetic field in the solenoid.

force = N [2]


11
(iii) A small piece of paper of mass 0.10 g is placed on the side DQ and
positioned so as to keep the frame horizontal. Given that QC is of length 15.0
cm, how far from the knife-edge must the paper be positioned?

distance = m [2]

(d) State Faradays and Lenzs laws of electromagnetic induction.

[2]

(e) A pair of concentric coils is shown in Fig. 3.3.

Fig. 3.3


12

The outer coil X has 2500 turns and is connected to a variable power supply by the
terminals CD. The inner coil Y has 500 turns, a cross-sectional area of
7.25 x10
-4
m
2
and a resistance of 5.00 . Coil Y is connected to a resistor R of
resistance 5.00 .
The variation with time t of the magnetic flux density B in coil Y is shown in Fig. 3.4.

(i) Calculate the maximum current in R.

maximum current = A [3]

(ii) On Fig. 3.5, sketch the variation with time t of current I in R. [3]

Fig. 3.4
Fig. 3.5


13
(iii) Discuss the change in the answer to (e)(i), if any, when the number of turns in
inner coil Y triples to 1500.

[3]


14

4 (a) In a photoelectric experiment, metal G and metal F are illuminated with a light
source in an evacuated photocell and photoelectrons are emitted.
Each metal occupies an equal surface area. Fig. 4.1 shows the variation of the
stopping potential V
s
for metal G with frequency f of the light source.

(i) State what is meant by the work function of a metal.

[1]

(ii) Metal F has a work function of 0.125 eV.
Calculate the threshold frequency for photoelectrons to be emitted from metal
F.

threshold frequency = Hz [2]

(iii) On Fig. 4.1, sketch the variation of stopping potential V
s
for metal F with the
frequency f of light source. Label your sketch F. [2]
V
s
/ V
f / 10
13
Hz
Hz
metal G
2.60
Fig. 4.1


15
(iv) Electrons emitted from the surface of metal G and metal F are collected at
plate D as shown in Fig. 4.2.

1. State whether metal G or metal F emits electrons with a higher
maximum kinetic energy. Explain your answer.

[2]

2. The current detected in the ammeter is reduced to zero when the
potential at metal G and metal F is 8.00 V and the potential at plate D is
5.00 V.
Determine the corresponding frequency of the light source.

frequency = Hz [3]

A
metal G and
metal F
Plate D
Light source
Fig. 4.2


16
(b) Fig. 4.3 shows the variation of intensity I with wavelength of an X-ray spectrum.

Fig. 4.3

(i) Explain the origins of the features of the X-ray spectrum using quantum
theory.

[5]

I

0
min


17
(ii) The spectrum is obtained from an X-ray machine in which electrons are
accelerated through a potential difference of 40 kV.
Calculate the minimum wavelength
min
.

minimum wavelength
min
= m [2]

(iii) On Fig. 4.3, sketch the spectrum which would be obtained from the same
machine when the accelerating voltage is halved. [3]

End of paper

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JJC 2013 9646/JC2 CT2 P1/2013 [Turn Over

JURONG JUNIOR COLLEGE

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