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Questions on colour

Q2.

(a) Peter tried to obtain a mixture of red and green light. He used white light from a spotlight and slotted a red filter and a green filter in front of it as shown below.

z

The diagram below represents Peter’s experiment.

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(i) No light reached the screen. Explain why. (2 marks)

The red filter only allows red light to pass through it. It absorbs all of the other colours in the white light. Therefore only red light reaches the green filter. The green filter only allows green light to pass through it. It absorbs the red light. Therefore no light comes through the filter combination.

(ii) Peter cut a circular hole in the green filter. Describe what Peter would see on the screen. (1 mark)

A red circle of light

(b) Peter used two spotlights to shine a mixture of red and green light on to some red curtains.

(i) What colour did the red curtains appear in this light? (1 mark)

Red

(ii) Give the reasons why they appeared this colour. (2 marks)

The red curtains will scatter red light and absorb all other colours. They will therefore scatter the light from the red spotlight and absorb the light from the green spotlight.

Maximum 6 marks