Download Wave Light Test

Name .........................................
Kingswood College 2004
PHYSICS UNIT 1 - SIGHT AND LIGHT TEST
TOTAL: 60 Marks
1)
1.
2.
Answer all Multiple Choice questions in the grid below
5)
9)
13)
2)
6)
10)
14)
3)
7)
11)
TOTAL =
4)
8)
12)
A virtual image formed by a plane mirror is always:A.
upright
B. On the same side of the mirror as the object
C.
enlarged
D. Further away from the mirror than the object
The image produced by a plane mirror is :
A.
real
B. virtual
C.
either real or virtual as it depends on the distance of the object from the mirror
For Questions 3 and 4
A girl walks away from a plane mirror at a speed of 1.2m/s (metres per second).
3.
What is the apparent speed of separation between herself and her image
A.
4.
B.
1.2m/s
C.
2.4m/s
D.
3.6m/s
If she is walking due West then what direction is the image walking.
A.
5.
0m/s
West
B.
South
C.
North
D.
East
Three light rays from an object placed to the left of a convex lens are shown below.
Which one of the following correctly describes the image formed by the lens?
A. virtual, upright and larger than the object
B. virtual, inverted and smaller than the object
C. real, upright and smaller than the object
D. real, inverted and larger than the object
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6.
The following diagrams show rays of light reflected by a spherical concave mirror. The point
C represents the centre of curvature and ƒ, the focal point.
Which of the diagrams best shows the paths of a light rays reflected by a concave mirror?
A
B
ƒ
ƒ
C
C
C
D
ƒ
ƒ
7.
8.
C
C
A real image formed by a convex lens is always:
A. enlarged
B. inverted
C. diminished
D. upright.
The diagram below shows a single light ray passing through water and incident on the
boundary between the water and air at P. The magnitude of the critical angle is also shown.
A
B
air
P
C
water
Incident ray
D
Critical
Angle
Which one of the four lines, A - D, shows the path followed by the light ray after it leaves P?
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9.
A narrow beam of white light (W) hits the side of a prism. Which diagram best shows the
paths of the red light (R) and violet light (V) as they pass through the prism and emerge on the
other side.
A
B
C
R
R
V
V
E
D
V
R
F
R
V
V
R
R
V
10.
A mixture of red and blue light is incident to a glass prism along the path PQ as shown below.
Q
P
Z
Y
V
W
X
The paths of the emerging beam of red light are maked as W and Y on the diagram. Which of
the choices (V - Z) could represent the path of the blue light emerging from the prism?
11. Choose the correct statement below. A yellow filter:
A.
absorbs yellow light and reflects all other colours
B.
reflects yellow light and absorbs all other colours
C.
transmits yellow light and reflects all other colours
D.
transmits yellow light and absorbs all other colours
12. Under white light, a red object appears red. If you now viewed the object through a blue
filter, what would the object look like?
A.
Blue
B.
Red
C.
Dark (or no light)
D.
Magenta
E.
White
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13. When white light is incident upon a prism dispersion occurs. Dispersion of white light is:
A. light being spread out into its spectral colours by diffraction
B. light being scattered because of impurities in the substance
C. different wavelengths of light being refracted by different amounts
D. a phenomenon only seen around stars at night
14. When light of one wavelength is directed towards an opaque object that has a sharp edge, a pattern of
light results (as shown below).
Which particular effect of light is responsible for the pattern?
A. Diffraction
B. Dispersion
D. Polarisation
E. Scattering
C. Interference
Short Answer Section (Write your answers in the space provided)
1.
An object (the arrow) is placed at X in front of a parabolic mirror. ƒ is the mirror's focal point.
Y
ƒ
X
Z
a) On the diagram, locate the position of the image of the object
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M irror
b) Use the following key in answering parts I), ii) and iii) of this question
Key:
A.
C.
E.
Erect, real, magnified
Inverted, real, magnified
Erect, virtual, diminshed
B.
D.
F.
Inverted, real, diminished
Inverted, virtual, diminished
Erect, virtual, magnified
i) Which of the above would describe the image formed when the object is at X?
ii) Which of the above would describe the image formed when the object is at Y?
iii) Which of the above would describe the image formed when the object is at Z?
(2+1+1+1=5 marks)
2.
The diagram below shows a plane mirror on a wall in a darkened room. The only source of
light is from a small white light in the position shown.
WALL
Z
Mirror
Y
A
B
X
W
s ource
M
a)
Mark and label the position of the image of the light source in the plane mirror.
b)
Draw two rays from the light source to the points A and B. Continue these rays to show
their path after reflection. Show any construction.
c)
Which of the observers W, X, Y or Z can see the image of the source?
(one or more answers)
d)
An observer at M notices that he cannot clearly see the mirror. The best explanation for
this is: (Circle the best answer)
A.
The metal surface at the back of the mirror absorbs most of the light
B.
The mirror produces a virtual image and not a real one.
C.
The wall reflects all of the colours of the spectrum
D.
None of the light incident upon the mirror is reflected into the observer's eye.
(1+2+1+1=5 marks)
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3.
The camera shown is adjusted correctly to take a sharply focussed picture of the object arrow.
movable lens
Object
Film
a)
locate and label the image of this arrow formed by the camera lens
b)
c)
locate and label both foci of the lens
With the lens is this position, very distant objects will appear fuzzy or out of focus in the
photograph. Explain why. You may use the diagram above to draw rays to support your
answer.
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d)
4.
In what direction should the lens be moved to produce a sharp photograph of the very
distant object?
(2+1+2+1=6 marks)
A parallel-sided block of glass is partially immersed in a liquid as in the diagram. A ray of
yellow light is incident on the face exposed to the air at an angle of 60 degrees. Its subsequent
path is shown.
60°
air
nair = 1
30°
liquid
45°
Using sin 45° = 0.7, sin 30° = 0.5, sin 60° = 0.87
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a)
Calculate the refractive index of the glass
b)
Calculate the refractive index of the liquid
c)
Another ray is travelling through the glass towards the air. What angle of incidence at the
top surface would cause the emerging ray to travel along the glass face?
d)
What would happen to the light if the angle of incidence was larger?
(2+2+2+2=8 marks)
5. The diagram below shows a light wave. It takes 5.0 x 10-9 s for a wave trough at A to reach B.
B
A
150 cm
a) What is the wavelength?
b) What is the period of the wave?
c) What is the speed of the wave?
(2+2+1=5 marks)
6. When orange light of frequency 4.8 x 1014 Hz traveling through the air meets a glass prism its speed
decreases from 3.0 x 108 ms-1 to 2.0 x 108 ms-1. Calculate the wavelength of the orange light in
a) the air
b) the glass
(2+2=4 marks)
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7. A simple optical fibre consists of a cylindrical tube of transparent material of refractive index 1.50
surrounded by air. A light ray is retained within the fibre by total internal reflection. The light ray
travels down the tube striking the wall at an angle, .
a) Find the maximum value of the angle  for which the light will satisfactorily travel through the
tube. The speed of light in air is 3 x 108 ms-1.
b) What is the speed of light in the material of the optical fibre?
(2+2=4 marks)
8. Colourful patterns often appear on oil found on wet road surfaces and driveways.
Using a diagram of a side-on view showing the oil/water surface, explain why several colours are usually
seen in the pattern.
(5 marks)
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9. Both microwaves and visible light are parts of the electromagnetic spectrum and display the same wave
properties. A microwave transmitter produces plane-polarised waves.
A wire grid is placed in front of the transmitter as shown below. It is rotated in the plane ABCD. A
maximum value of 100 mA is obtained on the meter when the wires are horizontal, and a zero reading is
obtained when the wires are vertical.
Explain what is meant by the term 'plane-polarised' and why the receiver’s current changes when the wire
grid is rotated.
(4 marks)
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END OF TEST
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