St. Paul’s Secondary School
First Term Test 2020 – 21
Physics
Form 3
Form 3 _____ Name _____________________ No. ______
Stationery: Question-answer paper only
Total number of pages of question paper: 8
Time allowed: 30 minutes
Instruction to students:
Answer all questions. Hand in the whole paper intact.
SECTION A (10 marks)
Choose the most appropriate answer for each of the following questions and fill in the corresponding table on
each page of the test paper.
1.
A ray of light hits a plane mirror as shown below. Find θ.
A. 70°
θ
B. 120°
C. 140°
D. 160°
20°
2.
A ray of light is directed normally to a plane mirror as shown. If the mirror rotates in clockwise sense
through an angle of 15°, what is the angle that the reflected ray rotated?
A. 0°
B. 15°
C. 30°
D. 60°
Question No.
1
Answer
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2
3.
John stands in front of a plane mirror in which he sees the image of three letters ‘PHY’ posted on the wall
behind him.
Which of the following is the image he sees?
A.
B.
C.
D.
4.
Alice is having a party with her friends. She lights the candles on a birthday cake and turns off the lamps in
the room.
Which of the following statements is/are correct?
(1)
(2)
(3)
A.
B.
The lamps become non-luminous when they are turned off.
Alice can see the cake because it is luminous.
The candle flame gives out a parallel light beam.
(1) only
(3) only
C. (1) and (2) only
D. (1) and (3) only
Question No.
3
Answer
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Page 2
4
5.
Ivan of height 1.8 m checks his appearance from a plane mirror before he leaves home for school. His eyes
are 10 cm below the top of his head. The ray diagram below shows that he can just see his whole body in
the mirror.
Ivan
Ivan’s image
Which of the following statements is/are correct?
(1) The minimum length of the mirror is 0.9 m.
(2) His image will be larger if he walks towards the mirror.
(3) He can only see part of his image if he walks towards the mirror.
A.
B.
C.
D.
6.
(1) only
(3) only
(1) and (2) only
(2) and (3) only
A light ray falls onto different surfaces. Which of the following situations is impossible?
A.
B.
white paper
plane mirror
C.
D.
black paper
glass sheet
Question No.
5
Answer
F3 Phy
Page 3
6
7.
When an object is placed in front of a mirror, we can only see its image in the mirror. We cannot see the
image behind the mirror.
Which of the following statements about the image is/are correct?
(1)
(2)
(3)
A.
The image cannot be formed on a screen.
The image is virtual.
The image can be smaller than the object.
(1) only
B. (3) only
C. (1) and (2) only
D. (2) and (3) only
8.
Tom hides at the corner as shown in the figure. Where is the image of Tom as seen by his mother?
A. At P
B. At Q
C. At R
D. At S
Question No.
7
Answer
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Page 4
8
9.
Which of the following statements about a point luminous object are correct?
(1) For an observer very far away from the object, light rays from the object are parallel.
(2) For an observer near the object, light rays from the object are divergent.
(3) For an observer very close to the object, light rays from the object are convergent
A. (1) and (2) only
B. (1) and (3) only
C. (2) and (3) only
D. (1), (2) and (3)
10. An object O is placed in front of a plane mirror as shown. An observer at P sees the image I of O in the
mirror.
 P
O
mirror
I
Which of the following statements is/are correct?
(1) If the observer moves to another position, he will find that the position of the image I changes.
(2) If the observer moves to the same position as O, he cannot see the image I.
(3) If the mirror is moved towards P, the image I will move towards O.
A.
B.
C.
D.
(1) only
(1) and (2) only
(2) and (3) only
(1), (2) and (3)
Question No.
9
Answer
End of Section A
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10
Section B (20 marks)
11. The image of the bird is blurred when there are small ripples in water (Figure A). In contrast, the image of
the beautiful nature scene, formed by the calm water of the lake, is very sharp (Figure B).
Figure A
Figure B
(a) Name the type of reflection in Figure B.
(1 mark)
(b) With the aid of a ray diagram, briefly explain the type of reflection leading to the formation of the
blurred image of the bird in Figure A.
(4 marks)
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12. State the Laws of Reflection.
(2 marks)
13. The figure below shows a point object O, two observers A and B, and a mirror M.
A
B
O
M
(a) On the above diagram, mark the image position of O as I.
(2 marks)
(b) There is only one observer who can see the image in part (a). Show which observer, A or B can see the
image.
(3 marks)
(c) Suggest how M should be moved so that both A and B can see the image.
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(2 marks)
14. An observer sees an image PʹQʹ of an object PQ in a plane mirror, as shown in the figure below.
Qʹ
observer
image
Pʹ
(a) Draw the object PQ in the figure.
(1 mark)
(b) Draw two cones of ray to show how the observer sees the whole image.
(3 marks)
(c) State the change in the image if
(i) the object moves upwards by one unit;
(1 mark)
(ii) the observer moves to the left by one unit?
(1 mark)
End of Test
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St. Paul’s Secondary School
F. 3 Physics 2nd Test 2020 – 21
Suggested Answers
Section A (1 mark for each correct answer)
1.C
2.C
3.D
4.A
5.A
6.A
7.C
8.A
9.A
10.C
Section B
Question 11
Marks
(a) Regular reflection
1A
(b) Graph with a rough surface.
1A
Graph with normals pointing at different directions.
1A
When parallel light rays from the mountain hit the water surface,
1A
the reflected rays are not parallel.
1A
Question 12
The laws of reflection states that the angle of incidence is equal to the angle of reflection.
1A
The incident ray, the reflected ray and the normal all lie on the same plane.
1A
Question 13
A
B
O
M
I
(a)
(b)
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Image position correct.
Label I
Straight line joining AI.
Straight line joining BI.
1A
1A
1A
1A
Only B can see the image.
1A
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(c)
M moves to the right by 5 units.
(Accept any answers that are correct.)
(Award 1 mark if only A or B can see the image.)
2A
Question 14
Qʹ
Pʹ
P
Q
(a)
Correct object
1A
(b)
Correct cones of ray drawn from P or Q
Correct incident rays
ALL correct
(c)
(i)
The image would move to the left by one unit.
1A
1A
1A
1A
(ii)
The image would not change.
1A
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