Light (Cambridge (CIE) IGCSE Physics): Exam Questions

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.

(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]

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.

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.

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.

[3]

(ii) Ring all of the following distances that are equal to the focal length of the lens.                                                            

[2]

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

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.

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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The speed of a light wave in air is 3.00 × 10⁸ m / s. The refractive index of water is 1.33.

Calculate the speed of the light wave in water.

speed = ......................................................... 

Fig. 7.1 shows parallel wavefronts of a light wave in air incident on a boundary with a transparent plastic.

On Fig. 7.1,

(i) draw the positions of the four refracted wavefronts in the plastic,

[3]

(ii) draw an arrow to show the direction of travel of the refracted wave,

 [1]

(iii) label the angle of refraction r of the light wave.

[1]

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.

(i) On Fig. 6.1:

1. Continue the ray of light from the golfer towards the upper mirror of the periscope.

   • 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]

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

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

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

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.

Extended tier only

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

Fig. 8.1 is a partially completed ray diagram.

The object is at O and its image is at I.

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

  C to F₁ 

 O to C

 F₂ to I

 O to I

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

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.

Fig. 8.1 shows a ray of light travelling through a glass block and then reflecting from a mirror.

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

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

 angle of incidence

 angle of reflection

 angle of refraction

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.

Extended tier only

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

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.

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]

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.

Fig. 6.1 represents the electromagnetic spectrum.

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

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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. 

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]

Extended tier only

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

The refractive index of diamond is 2.42.

Calculate angle x.

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

Explain the term total internal reflection.

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.

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

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

Extended tier only

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

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]

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

(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]

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

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.

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

(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]

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

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.

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]

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

(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]

(iii) Determine the height of the image.

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

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

[1]

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.

(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]

Extended tier only

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

(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]