Colour and lenses test with answers for grade 8 science (free PDF download)

Question 1 White light and a prism (2 marks)

A narrow beam of white light passes through a glass prism onto a screen.

1. Describe what you see on the screen. (1 mark)
2. Then state which colour bends the most. (1 mark)

Question 2 Magenta filter (2 marks)

You place a magenta filter in a beam of white light.

1. State the colours of light that the filter transmits. (1 mark)
2. Now you shine green light alone at the filter. State what emerges and why. (1 mark)

Question 3 Leaf in red light (3 marks)

You view a green leaf in white light and then in pure red light.

1. Explain why the leaf looks green in white light. (1 mark)
2. Then explain why the leaf looks black in red light. (2 marks)

Question 4 Magnification (2 marks)

A student looks at a coin 2.4 cm wide through a lens, and the image is 9.6 cm wide.

1. Calculate the magnification. (1 mark)
2. Then a different lens has a magnification of 0.60, so calculate the image height of a 5.0 cm object. (1 mark)

Question 5 Parts of the eye (3 marks)

Name the part of the eye that:

1. changes the size of the pupil; (1 mark)
2. contains the light-sensitive cells; (1 mark)
3. carries signals to the brain. (1 mark)

Question 6 Image on the retina (2 marks)

Describe the image that forms on the retina of a person looking at a tree. Then give two features. (2 marks)

Question 7 Reading a lens diagram (3 marks)

The diagram shows parallel rays passing through a lens, and then meeting at a point.

1. Name this type of lens. (1 mark)
2. Then state the focal length of the lens. (1 mark)
3. State where the image of a very distant tree would form. (1 mark)

Question 8 Object close to a lens (3 marks)

A student holds a converging lens of focal length 10 cm and places a small object 4 cm from it.

1. Firstly, describe the image. (1 mark)
2. Then explain why you cannot catch the image on a screen. (1 mark)
3. State a use of a lens in this way. (1 mark)