San Ġorġ Preca College Secondary School, Blata l-Bajda
Half-Yearly Examinations - February 2015
PHYSICS
Track 3
Form: 4
Name & Surname:
Time: 1 hour 30 min
Class:
Index No:
Teacher:
Answer ALL questions in the spaces provided on the Examination Paper.
All working must be shown. The use of a calculator is allowed.
Where necessary take the acceleration due to gravity g = 10 m/s2.
Good Luck!
Equations for Half-Yearly Exam Physics
Optics
height of image
magnification
magnification = image distance
object distance
height of object
speed of light in air
refractive index of glass or water =
speed of light in glass or water
refractive index of glass or water =
Waves
Speed = distance
time
Electricity
Q = I t
v = fλ
real depth in glass or water
apparent depth in glass or water
T =1
f
f = number of waves
time
Marks Grid: For the Examiners’ use ONLY
Question No.
1
2
3
4
5
6
7
8
Theory
Practical
Total
Max. Mark
8
8
8
8
8
15
15
15
85
15
100
Score
Track 3/Form 4/Page 1 of 10
Section A
This section carries 40 marks.
1.
The figure represents a ray of light striking and being reflected by a plane mirror AB.
a.
Complete the following statements:
i.
HO is the __________________ray.
ii.
________ is the reflected ray.
iii.
The angle between the normal and the
A
1
H
1
e
plane mirror AB = ______ .
O
1
50
iv.
Angle e is the angle of________________.
v.
The angle of reflection = _______.
1
L
1
B
b.
The figure shows an object O placed 2.5 m away from a plane mirror MM’ and its
image I appearing inside the mirror. An observer Y is standing 1.5 m away from the
object O as shown.
M
I
O
Y
1.5 m
2.5 m
M’
i.
The image I appears to be __________ m behind the mirror.
1
ii.
The distance of the observer Y from the mirror MM’ =
_____ m.
1
iii.
The distance between the object O and the image I
_____ m.
1
2.
Light waves can be reflected, refracted and diffracted.
a.
Underline the correct word within brackets in the statement below:
=
(Reflection/ Refraction/ Diffraction) is the change in direction of a ray of light due
to change in its speed, when it travels from one medium to another.
Track 3/Form 4/Page 2 of 10
1
b.
A pebble at the bottom of an aquarium appears closer to the surface at Q as shown in the
figure below:
B
aquarium
12 cm
O
water
44 cm
Q
8 cm
P
pebble
i.
Name the incident ray. _____
1
ii.
Mark the angle of refraction using the letter ‘r’.
1
c.
Calculate the:
i.
depth of the water in the aquarium in cm,
1
ii.
real depth of the pebble in cm,
1
iii.
apparent depth of the pebble in cm,
1
iv.
refractive index of the water in the aquarium.
2
3.
a.
The figure below represents a photograph of a wave travelling along a rope held
firmly at end R.
R
i.
What kind of wave is set up in the rope shown in the above diagram?
___________________________.
1
ii.
On the wave diagram mark one crest with the letter ‘C’
1
iii.
On the wave diagram mark one wavelength using the Greek letter ‘’.
1
Track 3/Form 4/Page 3 of 10
b.
A water wave is set up in a large ripple tank as shown below.
0.8 m
0.5 m
2.0 s
Use the water wave diagram, calculate the:
i.
wavelength in m,
ii.
frequency of the wave in Hz,
2
iii.
velocity of the wave in m/s,
iv.
amplitude of the wave in m,
2
v.
periodic time of the wave in s.
4.
a.
i.
A sound wave is a _________________________ wave.
1
ii.
A sound wave is made up of_________________________ and rarefactions.
1
iii.
Sound waves do not travel through a ____________________ .
1
iv.
Human beings can hear sounds of frequencies between 20 Hz and _________________.
1
b.
Underline the correct word within brackets in the statements below:
i.
Sound waves travel (faster/ slower/) through air than through water.
ii.
The velocity of sound wave depends only on the (frequency of the sound wave/
1
Complete the following statements about sound.
loudness of the sound wave/ medium through which the sound wave travels).
c.
1
1
A sound note of frequency 1320 Hz is emitted into the air. Calculate the wavelength of
2
the emitted note given that the speed of sound in air is 330 m/s.
Track 3/Form 4/Page 4 of 10
5.
a.
Draw the charges present on the perspex (or cellulose acetate) strip and on the
polythene strip after Claire rubs them with a dry cloth.
perspex (or cellulose acetate) strip
b.
polythene strip
2
Claire hangs the charged perspex (or cellulose acetate) strip using a string as shown in
the diagram below.
string
stand
charged perspex (or cellulose acetate) strip
Underline the correct word in brackets to show what Claire observes when she brings a:
i.
charged polythene strip close to the suspended charged perspex or cellulose acetate
strip: (attraction/ repulsion/ neither attraction nor repulsion)
ii.
1
a charged perspex or cellulose acetate strip close to the suspended charged perspex
or cellulose acetate strip: (attraction/ repulsion/ neither attraction nor repulsion)
c.
1
Clare decides to rub the perspex (or cellulose acetate) strip with a damp (wet) cloth in
order to charge it.

Will she be successful? __________
1

Explain why.
1
d.
Calculate the time taken for 420 C of charge to flow through a motor given that it runs
on a current of 6 A.
2
Track 3/Form 4/Page 5 of 10
Section B
This section carries 45 marks.
6.
This question is about the laws of reflection.
a.
The diagram shows how the image of sponge bob is seen in a plane mirror by Tony.
Tony
i.
Draw arrows on the rays of light to show the direction along which light travels.
2
ii
Draw the normal.
1
iii.
The angle between the incident and the reflected rays is 140 °.
Calculate the angle of incidence.
1
iv.
Explain why the rays behind the mirror are dotted.
1
v.
Name two other properties of the image produced by the plane mirror.
2
Track 3/Form 4/Page 6 of 10
b.
Yanica is investigating the relationship between the angle of incidence and the angle of
reflection. She writes down the method she used as shown below.
Fill in the missing words by choosing the correct word from the list below:
ruler; incident; ray box; normal; protractor; mirror
Method
1.
A line is drawn on a white sheet of paper and a plane _________________ is
vertically and accurately placed on the line.
1
2.
A ray of light from the ___________________ is set on towards the plane mirror.
1
3.
The ____________________ and the reflected rays are each marked by two dots.
1
4.
The mirror is removed and a ____________________ is used to draw a line to
join the dots in order to show the paths of the two rays of light.
5.
The ___________________ is drawn at the point where the two rays meet (hit)
the plane mirror.
6.
1
A ____________________ is used to measure the angle of incidence and the
angle of reflection.
c.
1
Write down the conclusion Yanica reaches based on the results of her investigation
assuming that she did not commit any mistakes.
d.
1
1
Name one precaution Yanica takes during the experiment in order to obtain accurate
results.
1
Track 3/Form 4/Page 7 of 10
7.
This question is about electromagnetic waves.
a.
The diagram below shows the dispersion of white light by an equilateral glass prism.
screen
white light
red light
air
equilateral glass prism
violet light
State which of the following statements are TRUE or FALSE in the spaces provided.
i.
The prism does not add colours to white light but only separates all the colours which
make up white light.
ii.
_______________
1
The separation of white light into the seven colours of which it is made up of is referred
to as dispersion.
_______________
1
iii.
All colours which make up white light are longitudinal waves.
_______________
1
b.
The diagram below represents the electromagnetic spectrum.
visible light
gamma
rays
x-rays
P
Q
microwaves
radio waves
i.
Name the missing radiations P and Q in the above diagram.

P = ____________________
1

Q = ____________________
1
Track 3/Form 4/Page 8 of 10
ii.
Name the radiation which:

has the shortest wavelength and the highest frequency,
____________________
1

has the longest wavelength and the lowest frequency,
____________________
1

can be felt but not seen,
____________________
1

can be seen but not felt.
____________________
1
iii.
Which radiation is:

used to check for fractured (broken) bones?
____________________
1

used to treat cancer?
____________________
1

produced by the sun and can cause sunburn?
___________________
1

emitted (given out) by a heater making us feel warm?
____________________
1
c.
Calculate the frequency of radio waves of wavelength 3 m given that the speed of radio
waves is 3 x 108 m/s (300 000 000 m/s).
2
PLEASE TURN OVER FOR QUESTION 8
Track 3/Form 4/Page 9 of 10
8.
This question is about converging lenses.
a.
An object O is 1.2 cm high stands 4.0 cm from the centre of a converging lens L of
focal length 2.5 cm.
L
•
•
i.
Complete the ray diagram by drawing two rays from the top of the object to form the
image.
2
ii.
Label the image I.
1
iii.
Underline the correct characteristic of the image in each of the following:

Real or virtual,
1

Upright or inverted,
1

Magnified, diminished or same size.
1
iv.
Measure the height of the image. ________ cm.
1
v.
Calculate the magnification of the lens.
2
b.
The table shows how the image distance of the lens changes when the object distance is
changed.
i.
ii.
object distance u / cm
5
6
8
12
15
image distance v / cm
20.0
12.0
8.0
6.0
5.5
Plot a graph of image distance v (y-axis) against object distance u (x-axis) on the graph
paper provided.
5
Use your graph to find the image distance when the object distance is 7 cm.
1
Track 3/Form 4/Page 10 of 10