6.13 Visible light, colour and reflection
9 exam questions worth 22 marks. Write your answer, open the mark scheme, then give yourself the marks you earned. Your answers are saved on this device.
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Which type of reflection happens at a mirror?
Choose one answer.
Correct Not quite: the answer is Specular reflection
Mark scheme
B: Specular reflection
Model answer
Specular reflection (B).
Explain why you can see a sheet of white paper from any direction, but you cannot see your face in it.
Mark scheme
the paper surface is rough (1); so light is reflected in many directions (diffuse reflection) (1); there is no clear image because the reflected rays are not parallel (1)
Model answer
The surface of paper is rough, so light is scattered in all directions (diffuse reflection). This lets you see the paper from any direction, but the reflected rays are not parallel, so there is no clear image.
State what happens to a ray of light that hits a rough surface, and explain why the reflected rays go in different directions.
Mark scheme
each ray is reflected obeying the law of reflection (1); the surface is made of many tiny surfaces facing different directions (1); so the normal is different at each point, and the rays are reflected in different directions (1)
Model answer
Each ray obeys the law of reflection, but the rough surface has tiny faces pointing in different directions. The normal is different at each point, so the rays are reflected in different directions.
Explain why a red book looks red in white light.
Mark scheme
it reflects red light (1); and absorbs the other colours (1)
Model answer
It reflects red light and absorbs the other colours of white light.
Explain why a green leaf looks black in red light.
Mark scheme
the leaf only reflects green light (1); there is no green in red light, so the red light is absorbed and nothing is reflected (1)
Model answer
A green leaf reflects only green light. There is no green in red light, so all of it is absorbed and the leaf looks black.
A white object is lit by green light. State the colour of the object and explain why.
Mark scheme
green (1); white reflects all colours, so the green light is reflected (1)
Model answer
It looks green, because a white object reflects all the colours that fall on it, which is only green.
State what is meant by a translucent material and give an example.
Mark scheme
light passes through but is scattered, so you cannot see clearly through it (1); e.g. frosted glass / tracing paper (1)
Model answer
Light can pass through, but it is scattered so you cannot see clearly through it, for example frosted glass.
White light passes through a blue filter. Describe what comes out of the filter and explain why.
Mark scheme
blue light (1); the filter absorbs the other colours / only transmits blue (1)
Model answer
Only blue light comes out, because the filter absorbs the other colours and transmits blue.
A stage lighting technician has a red costume, a green costume and a white costume. Describe how each would look under a red spotlight, and explain the difference.
Mark scheme
red costume looks red (1); green costume looks black (1); white costume looks red (1); red light is reflected by the red and white costumes (1); the green costume absorbs red light and there is nothing else to reflect (1)
Model answer
The red costume looks red and the white costume looks red, because both reflect red light. The green costume looks black, because it absorbs red light and there is no other colour in the light for it to reflect.
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