Light (Cambridge O Level Physics)

Exam Questions

3 hours44 questions
1a
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3 marks

The spectrum of white light is made up of seven colours.

Fig. 7.1 shows a partially-completed spectrum. Two labels are missing.

 
q7a1
 
(i)
On Fig. 7.1, write the name of the missing colour in each blank space.
[2]
 
(ii)
On Fig. 7.1, indicate the direction of increasing wavelength for the spectrum. Draw an arrow in the box below the spectrum of colours.
[1]
1b
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3 marks

A ray of red light strikes one face of a triangular glass prism as shown in Fig. 7.2.

 
q7b
 
(i)
On Fig. 7.2, draw the path of the ray as it travels through the glass prism and enters the air.
[2]
 
(ii)

State the term used to describe what happens to the ray of red light as it enters and leaves the prism.

[1]

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2a
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1 mark

Fig. 5.1 represents an object positioned on the principal axis of a thin lens.

q5a

Each small square of the grid represents 0.5 cm. Each principal focus of the lens is labelled F.
   

Use the grid to determine the focal length of the lens.

   
   
focal length = ..................................................... cm 
2b
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4 marks
(i)
On Fig. 5.1, draw a ray from the top of the object that passes through a principal focus, then through the lens and beyond it.
[1]
 
(ii)
On Fig. 5.1, draw a second ray from the top of the object that passes through the centre of the lens. Continue the path of this ray to the edge of the grid.
[1]
 
(iii)
On Fig. 5.1, draw an arrow to show the position and nature of the image produced by the lens.
[1]

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3a
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4 marks

An object, OX, is placed in front of a converging lens.

Fig. 7.1 shows a ray of light from the object passing through the lens.

screenshot-2022-10-13-at-13-28-24

(i)

The lens forms an image of object OX.

On Fig. 7.1, draw another ray from X to locate the position of the image.

[1]

(ii)

On Fig. 7.1, draw an arrow to represent the image of OX and label it I.

[1]

(iii)

On Fig. 7.1, mark a principal focus for the lens and label it F.

[1]

(iv)
On Fig. 7.1, measure and record the focal length of the lens.
 
focal length = ...................................................... cm [1]
3b
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2 marks

Describe the image I.

Choose words from the list. Tick () two boxes.

square enlarged

square diminished

square same size

square inverted

square upright

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4a
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2 marks

An endoscope is a piece of medical equipment used to see inside a person's body. Endoscopes use optical fibres within a long tube which reflects light from inside the patient to an eye piece lens or camera. 

 

3-2-4a-e-optical-fibre

Fig. 1.1

Fig. 1.1 shows a section of optical fibre. Light travels from X to Y.

 

On Fig. 1.1, complete the path of the light ray until it leaves the section of optical fibre.

4b
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1 mark

State the type of reflection that occurs within an optical fibre.

4c
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3 marks

Calculate the critical angle.

 

Glass has a refractive index of 1.52.

 
 
critical angle = ...................................

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5a
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3 marks

Fig. 1.1 shows a light ray passing though a block of ice. 

 

3-2-5a-e-refractive-index-of-ice

(not to scale)

Determine the refractive index of ice.

 
 
refractive index = .................................... 
5b
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3 marks

Explain why the angle of refraction is smaller than the incident angle for the boundary from air to ice.

5c
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1 mark

State the correct value of angle theta on Fig. 1.1.

 
 
angle theta = .................................... 
5d
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3 marks

Complete Table 1.2 by drawing a tick to show which properties of light change during refraction.

 
Property Does change Does not change
speed    
wavelength    
frequency    

Table 1.2

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1a
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2 marks

Fig. 9.1 shows two rays of light X and Y leaving an object O. The rays strike a plane mirror.


Ray X is reflected as shown.

rays

(i)
On Fig. 9.1, draw the normal at the point where ray X strikes the mirror.

[1]

(ii)
On Fig. 9.1, draw the path of ray Y after it strikes the mirror.

[1]

1b
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3 marks

An object O is placed on the left of a thin converging lens. F is the principal focus.

 
This arrangement is shown in Fig. 9.2.

lens

Two rays from the top of the object are incident on the lens, as shown in Fig. 9.2.

 
On Fig. 9.2, draw the path of each ray to locate the position of the image of O formed by the lens.

 
On Fig. 9.2, draw an arrow to represent the image and label it I.

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2a5 marks

Fig. 7.1 shows a converging lens and the image I formed when an object is placed to the left of the lens. The principal focuses are labelled A and B and the centre of the lens is labelled C.

(i)
On Fig. 7.1, draw two rays to locate the position of the object.
Draw the object and label it O.
                                                   
lens2
[3]
     
(ii)
Ring all of the following distances that are equal to the focal length of the lens.
                                                             
AB   AC CB 2AB
[2]
2b
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3 marks

Fig. 7.2 shows green light passing through a triangular glass block.

  prism

Red light enters the triangular glass block shown in Fig. 7.2 along the same path as the green light.

(i)
On Fig. 7.2, draw the path of the red light within the triangular glass block.
[1]
(ii)
Fig. 7.3 shows green light passing through a rectangular glass block.
Red light enters the rectangular glass block shown in Fig. 7.3 along the same path as the green light.
  
prism-2
  

On Fig 7.3 draw the path of the red light within the rectangular glass block.

[1]
(iii)
On Fig 7.3 draw the path of the red light after leaving the rectangular glass block.
[1]

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3a3 marks

Fig. 6.1 shows a mirror periscope. The periscope is used to view a golfer over the heads of other people. The periscope has two plane mirrors each at an angle of 45° to the vertical.

screenshot-2022-10-13-at-12-48-45

(i)
On Fig. 6.1:
1.
Continue the ray of light from the golfer towards the upper mirror of the periscope.
2.
Draw and label the normal at the point where the ray strikes the mirror.

[1]

(ii)
On Fig. 6.1, continue the ray of light after reflection at the upper mirror until it leaves the periscope.

[1]

(iii)
State the law of reflection used to deduce the position of the ray of light after striking the mirrors.

[1]

3b
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3 marks

Fig. 6.2 shows three rays of red light each entering a semi-circular glass block.

screenshot-2022-10-13-at-13-20-20

Using the information in Table 6.1, draw on Fig. 6.2 to complete the path of each ray of red light.

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4a
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3 marks

Fig. 6.1 shows an arrangement of glass prisms inside a box. The angles of the prisms are 45°, 45° and 90°.

may-june-2020-42-q6

 

This is a device used to view objects that are behind a wall.
The incident ray of light undergoes total internal reflection in the prisms.

 
On Fig. 6.1, complete the path of the ray through the device and show the ray as it emerges from the box.

4b
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2 marks

Show that the refractive index of glass with a critical angle of 45° is 1.41.

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5a
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1 mark
Fig. 8.1 is a partially completed ray diagram.
screenshot-2022-10-20-at-10-21-47
The object is at O and its image is at I.
  

Which distance is the focal length of the lens? Tick one box.

 

square  C to F

square  O to C

square  F2 to I

square  O to I
5b
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3 marks

On Fig. 8.1, extend the two rays from the arrowhead on the object until both reach the position of the image.

5c
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2 marks

The object is moved a small distance away from the lens. State the effect, if any, this has on the position and size of the image.

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6a
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1 mark
Fig. 8.1 shows a ray of light travelling through a glass block and then reflecting from a mirror.
screenshot-2022-10-31-at-14-05-49

State the term used for the dashed lines drawn in Fig. 8.1.

6b
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3 marks

Use Fig. 8.1 to identify the three angles in the list. Place the correct letter in the box to indicate each angle.

   

square  angle of incidence

square  angle of reflection

square  angle of refraction

6c
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2 marks

The ray of light in Fig. 8.1 changes direction as it enters the glass block. State the name of this effect and explain why it happens.

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7a
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1 mark

Fig. 5.1 shows part of the ray diagram of a lens being used as a magnifying glass. 

Three rays are shown coming from the top of an object O.

The points labelled F are one focal length from the lens. 

q5-cie-ol-physics-paper-2-2021-sq

Fig. 5.1

State the name of the type of lens shown in Fig. 5.1.

7b
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2 marks

Describe what happens to the ray of light R:

• as it enters the lens ...........................................................................

• as it leaves the lens. ..........................................................................

7c
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2 marks

Using all three rays from O, complete Fig. 5.1 to show the image formed.

7d
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1 mark

Underline all of the words in the list that describe the image formed in (c).

inverted       upright       real       virtual

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8a
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1 mark

Fig. 5.1 shows light in air, incident on the side of a rectangular glass block at an angle of 60°.

q5-cie-ol-physics-specimen-paper-2-sq

Fig. 5.1

The refractive index of the glass is 1.6. The light travels in the glass and is incident on side XY at P.

Underline all the terms that describe a wave of light.


    electromagnetic    longitudinal    radioactive   transverse

8b
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2 marks

At the point where the light enters the glass, the angle of refraction is r.

Calculate angle r.

r = ........................................................ °

8c
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4 marks
(i)
Calculate the critical angle c for light travelling in the block.

c = ........................................................ ° [2]
 

(ii)
At P, the angle θ between the ray and the normal is given by θ = 90° – r.

State and explain what happens to the light when it is incident on side XY.

 [2]

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1a
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1 mark

A laser produces a beam of monochromatic light. State what is meant by the term monochromatic.

1b
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6 marks

A wave, in air, is incident on a glass block. Fig. 7.1 shows the wavefronts at the air-glass boundary. The arrow shows the direction of travel of the wavefronts.

 

18p4-4a

The wave undergoes reflection and refraction at the air-glass boundary.

 
On Fig. 7.1 draw:

 
(i)
the wavefronts of the reflected wave
[3]
 
(ii)
the wavefronts of the refracted wave.
[3]
1c
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2 marks

A transverse wave is produced in a long, horizontal rope. The rope is much longer than the wavelength of the wave.

 
In the space below, sketch a diagram to show the appearance of the rope as the wave passes along it. Label two important features of the wave.

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2a
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2 marks

Fig. 6.1 represents the electromagnetic spectrum.

 
feb-march-2018-42-q6a
 

State the radiation in each of the regions represented by A, B, C and D in Fig. 6.1.

2b
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6 marks

A source emits visible light.

  

Fig. 6.2 shows a ray of red light from the source incident on the face XY of a glass prism at point S. 

 

feb-march-2018-42-q6b
 

The angle of incidence i of the ray is 35 °. The refractive index of the glass for red light is 1.5.

  

(i)

Calculate the angle of refraction in the glass at S.

angle of refraction = ......................................................... [2]

 

(ii)
On Fig. 6.2, draw the refracted ray at face XY and the ray emerging from face XZ of the
prism. Label this ray R.
[2]
 
(iii)
A ray of blue light follows the same path as the ray of red light incident on the face XY.
 
On Fig. 6.2, draw the path of this ray in the prism and emerging from the prism.
 
Label this ray B.
[2]

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3a
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2 marks

Fig. 7.1 shows red light travelling from air into a prism made of diamond. The path of the red light is incomplete.

q7

The refractive index of diamond is 2.42.

Calculate angle x.

 

 

angle x = .........................................................

3b
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3 marks

Explain the term total internal reflection.

3c
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2 marks

The angle y is greater than the critical angle of diamond.

 
On Fig. 7.1, draw the path of the red light through and out of the prism after point A.

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4a
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2 marks

Fig. 7.1 shows a ray of light in water that is incident on a submerged, transparent plastic block.

biktE7P7_q7a

State what happens to the speed of light as it enters the plastic block. Explain your answer.

4b
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6 marks

Fig. 7.2 shows the two principal focuses F1 and F2 of a thin converging lens.

PxbhBJ4J_q7b

Fig. 7.2 also shows an object O of height 1.2cm placed close to the lens. Two rays from the tip of the object O are incident on the lens.

 
(i)
On Fig. 7.2, continue the paths of these two rays for a further distance of at least 5 cm.
[2]
 
(ii)
Using your answer to (b)(i), find and mark on Fig. 7.2 the image I of object O and label this image.
[2]
 
(iii)

Determine the height of image I.

 

 

height = ...........................................................[1]

 

(iv)
State and explain whether I is a real image or a virtual image.
[1]

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5a
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4 marks

Fig. 7.1 shows a ray of light striking a plane mirror at point P.

  

cie-2020-31-10

 
(i)
Determine the value of the angle of incidence for the ray of light at point P.
 
 
angle of incidence = ...................................................... ° [1]
 

(ii)      On Fig. 7.1,

  • draw a normal at point P
  • draw the ray reflected at point P
  • determine the angle of reflection at point P.
 
 

angle of reflection = ...................................................... ° [3]

5b
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4 marks

Fig. 7.2 shows an object OB positioned 20cm from a thin converging lens. Both principal focuses of the lens are labelled F.

  

cie-2020-31-11

  

Two rays from the tip B of the object are incident on the lens, as shown in Fig. 7.2.

 

On Fig. 7.2, continue the paths of these two rays to show the position of the image of OB formed by the lens. Draw an arrow to show the size, position and orientation of the image of OB.

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6a
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3 marks

Fig. 6.1 shows a ray of red light incident on part of a lens.

18-32-3a

(i)
On Fig. 6.1, continue the path of the ray as it passes through the lens and emerges from it.
[2]
 
(ii)
State the term used to describe the process as the ray enters and leaves the lens.
[1]
6b
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2 marks

Fig. 6.2 shows two parallel rays of light travelling towards another lens.

 

18-32-3b

The two rays of light pass through the lens to form an image.

 
On Fig. 6.2, continue the path of the rays. Extend the rays for at least 5 cm beyond the lens.

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7a
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2 marks

A ray of light in air is incident on a glass block. The light changes direction.

State

 
(i)
the name of this effect.
[1]
 
(ii)
the cause of this effect.
[1]
7b
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6 marks

Fig. 5.1 shows a thin converging lens of focal length 3.5cm.

 
q5b
(i)
On Fig. 5.1, mark each of the two principal focuses and label each with the letter F.
[1]
 
(ii)
An object O of height 4.4cm is placed a distance of 7.5cm from the lens.
 
On Fig. 5.1, draw rays from the tip of the object O to locate the image. Draw and label the image.
[3]
 
(i)

Determine the height of the image.

 

 

height of the image = ...........................................................[1]

 

(iv)
State and explain whether the image is real or virtual.
[1]

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8a
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3 marks

Fig. 5.1 shows a visible spectrum focused on a screen by passing light from a source of white light through a lens and a prism.

p0Af0nGt_q5
(i)
State the name of the process that separates the colours in white light.
[1]
 
(ii)
State the colour of the light on the screen at points A and B.
[1]
 
(iii)

State the property of the glass of the prism that causes white light to be split into the different colours of the spectrum.

[1]

8b
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5 marks

Extended

Fig. 5.2 shows a section of an optical fibre in air. A ray of light is incident on the fibre wall at X.

q5b
(i)
On Fig. 5.2, continue the path of the ray of light up to the end of the fibre.
[1]
 
(ii)

The refractive index of the material of the fibre is 1.46. Calculate the critical angle of the material of the fibre.

 

 

critical angle = ...........................................................[2]

 

(iii)
State two uses of optical fibres.
[2]

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