Topic Menu

Cyber-chess a chess instruction site

GCSE level questions on light

Q1. (a) Some objects are transparent and some objects are opaque.

(i) Which one of the objects below is transparent? The glass vase

 

[1 mark]

(ii) Complete the sentence by choosing a wordfrom the table below:

'An opaque object does not transmit light.

Word to choose from
Tick here
absorb
reflect
  
transmit

 

[1 mark]

(b) A student wears a white T-shirt and a red baseball cap to a party.

(i) Explain why the T-shirt looks white in white light. whereas the blue baseball cap appears blue?

White objects reflect all visible light stimulating the red, blue and green cones in the observer's eyes, whereas blue objects absorb the wavelengths of light that would stimulate the red and green cones and reflect the wavelengths that stimulated the blue cones in the observer's eyes

[2 marks]

(ii) Explain how the colour of the T-shirt and baseball cap appear to change when the room lights at the party change from white to blue.

The white T-shirt now appears blue as there is only blue light for it to reflect and it reflects all wavelengths of light. The baseball cap can only reflect red light. As no red light is falling on it it looks black as it reflects no light.

[2 marks]

(c) Barry investigated how the type of surface affects the amount of infrared radiation the surface absorbs. The diagram belowshows the equipment that he used.

The metal sheets absorb infrared radiation. The wax melts and the drawing pins fall off the surfaces.

In the investigation there are several variables. Variables can be classifies as control variables, dependent variables and independent variables.

Complete the table to indicate the type of each of these variables:

Description
Variable type
Distance from the metal sheets to the infrared heater.
control
The surface colour of the metal sheets.
independent
Time taken for the drawing pins to fall off.
dependent

 

[3 marks]

(ii) What is the main hazard in this investigation?

The infra-red heater

For some reason the board gave no marks for saying you could burn yourself. Quote 'do not accept answers where burning yourself is given as the hazard'. You had to say which piece of equipment was the hazard not what the outcome of the hazard could be.... the heater could set things alight.... and okay it could burn you... or set your clothing alight... but they wanted you to identify the hazard not the outcome of the hazard.

[1 mark]

(iii) The drawing pin attached to the matt black metal sheet fell off first.

What can be concluded from this result?

The matt black surface absorbed the infra red radiation better that the shiny surface did. It therefore got hot more quickly.

To get the mark your answer must be a comparison - saying 'matt black is a good absorber' was insufficient.

[1 mark]

(Total 11 marks)