# Light and EM waves - Data response questions

Do not forget to take a ruler and calculator into the exam.

Maths questions often start with the command words like 'calculate', 'determine', 'estimate' and 'measure'. They will then include a blank space for you to show your working.

When an answer to a maths question is marked:

• full marks are given for the right answer (but it is wise to show your working so you can check your answer)
• marks are given for working, including substitution and rearrangement
• errors carried forward are taken into account

Errors carried forward are related to what happens if a later answer depends on an earlier answer, and you get the earlier one wrong. You could still get full marks in the later answer if your working is correct but you use the incorrect earlier answer.

If your answer has many decimal places or figures, make sure you give it to an appropriate number of decimal places or significant figures. You may be asked to give units. This may earn you an additional mark, so do not forget to check whether you need to do this.

Some maths questions might ask you to plot or complete a graph or table. When you draw a graph, make sure you:

• plot each point accurately
• draw a best-fit straight line or curve

You may be given a grid with axes and scales already given. Sometimes you may be given an empty grid for you to supply your own axes. When you do this:

• put the independent variable on the x-axis and the dependent variable on the y-axis
• make sensible scales so that the plotted points cover at least 50% of the area of the graph
• label the axes with their quantity and unit, eg time (s)

## Sample question 1 - Foundation

Question

The image below shows what happens when white light enters a glass prism; a spectrum of seven colours emerges:

a) The light has been 'bent'.

i) What is the correct name for the bending of light? [1 mark]

ii) Which colour is bent the most by the prism? [1 mark]

iii) Which is the middle colour of this spectrum? [1 mark]

iv) A student places a red filter in front of the beam of white light entering the prism. Describe what happens. [2 marks]

b) The student then went on to experiment with a piece of white paper and a red and green apple to investgate their appearance under different colour light conditions. Here is a table of the results but with four entries missing.

White paperRed appleGreen apple
Colour(s) that the object can reflectAllRed only...
Appearance of object in white lightWhite (no colours absorbed)...Green (all colours absorbed except green)
Appearance of object in red lightRed (only red light to reflect)RedBlack (no green light to reflect)
Appearance of object in green light...Black (no red light to reflect)...
Appearance of object in blue lightBlue (only blue light to reflect)Black (no red light to reflect)Black (no green light to reflect)

What are the missing entries? [4 marks]

This question has been written by a Bitesize consultant as a suggestion to the type of question that may appear in an exam paper.

a) i) Refraction

ii) Violet

iii) Green

iv) The filter absorbs all the colours apart from red. A red beam will enter the prism and emerge refracted from the other side.

b) The missing entries are:

White paperRed appleGreen apple
Colour(s) that the object can reflectAllRed onlyGreen only
Appearance of object in white lightWhite (no colours absorbed)Red (all colours absorbed except red)Green (all colours absorbed except green)
Appearance of object in red lightRed (only red light to reflect)RedBlack (no green light to reflect)
Appearance of object in green lightGreen (only green light to reflect)Black (no red light to reflect)Green
Appearance of object in blue lightBlue (only blue light to reflect)Black (no red light to reflect)Black (no green light to reflect)

## Sample question 2 - Higher

Question

A mobile phone network uses microwaves to transmit signals between mobile phones and masts. The microwaves have a frequency of 1.5 GHz and travel at a speed of 3 × 108 m/s. The maximum distance that a phone can be from a mast and still receive a signal is 35 km.

a) Recall an equation to calculate the wavelength of the microwaves. [3 marks]

b) Recall an equation to calculate the maximum time for a signal to travel from a phone to a mast 35 km away. [3 marks]

Question courtesy of Eduqas.

i) Conversion of 1.5 GHz to 1.5 × 109 Hz

So

ii) Conversion of 35 km to 35,000 m

speed = distance ÷ time

time = distance ÷ speed

= 35,000 ÷ (3 × 108)

= 1.17 × 10-4 s