Wave Interactions (OCR GCSE Physics A (Gateway))

A projector is used to create a larger image of an object.

The diagram shows one light ray as it passes through the convex lens.

Draw one more ray on the diagram to show where the image is formed. Label the image Y.

The projector contains a white light source.

Explain how this white light source can be used to get red light.

i) The projector is connected to the mains power supply. The projector has an earth wire.

State the potential difference between the earth wire and the live wire in normal use.

Potential difference = ................................................V[1]

ii) A projector with a plastic case does not need an earth wire. A projector with a metal case needs an earth wire.

Explain why.

[2]

A student investigates reflection and refraction of light rays.

The student sends a ray of red light into a glass prism.

Fig. 18.1 shows the light ray as it leaves the glass prism.

On Fig. 18.1 complete the ray of light as it travels towards and through the glass prism.

Fig. 18.1

Fig. 18.2 shows two mirrors placed at 90° to each other.

A light ray hits one of the mirrors at 45°.

On Fig. 18.2 complete the ray of light as it reflects from both mirrors.

Fig. 18.2

White light is made of different colours.

White light passes through a transparent filter X.

Filter X absorbs green, blue, indigo and violet light.

The light then passes through another transparent filter Y, as shown in Fig. 18.3.

Fig. 18.3

The light that leaves filter Y is red.

i) What colours are transmitted by filter X?

ii) What colours are absorbed by filter Y?

A wall is painted red.

When some coloured lights shine on it, the wall appears black.

i) Explain why.

ii) Suggest two different colours of light that would cause the wall to appear black.

.............................................and ............................................                                                                                      

An optician uses red and green light to test vision.

Fig. 18.4 is a ray diagram showing red light passing through a lens.

Fig. 18.4

i) Green light passes through the same lens as in Fig. 18.4.

Complete the ray diagram in Fig. 18.5 for green light. The focal point for red light F_R is shown.

Fig. 18.5

ii) Explain your answer to (e)(i).

iii) Is the lens in Fig. 18.4 and 18.5 suitable for correcting long-sight or short-sight?

Tick (✓) one box.

Explain your answer.

Lenses can be used to help people see clearly.

Fig. 18.1 is a diagram of a convex lens.

       Fig. 18.1

i) A student models the lens using two glass prisms and a glass block.

Complete the ray diagram Fig. 18.2 to show how light rays travel through the model lens (glass prism and glass block).

Fig. 18.2

ii) Explain how a convex lens can correct long-sighted vision.

      Use the model in Fig. 18.2 to help you.

A student looks at coloured paper in different coloured light.

Fig. 18.3 is a diagram of her experiment.

Fig. 18.3

She looks at red paper with red light. The paper appears red.

What colour does the red paper appear in blue light?

Explain your answer.

A candle is viewed in a mirror.

Complete the diagram to show the correct position of the candle and the path of the ray for the image viewed in the mirror.

Compare and contrast the interactions of specular reflection and scattering.

The diagram shows an object positioned close to a thin converging lens (inside the focal distance). Three light rays are shown leaving the object and passing through the lens.

Describe the location, type and size of image formed.

Explain the possible changes that could be made to the scenario in part (c) for a real image to be formed.