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GCSE questions on refraction and TIR

Q12. Nick used a ray box to shine a ray of light through air into a glass block.

He investigated how the angle of refraction varied with the angle of incidence.

The table below shows his results.

Angle of incidence in degrees
Angle of refraction in degrees
10
5
20
10
30
14
40
19
50
23
60
26
70
28
80
29

 

(a) Describe a method Nick could have used to obtain such results. Your answer may include a labelled diagram.

 

This type of question is marked in two ways:

- the examiner looks for relevant points

- but also for a logical sequence...

It is not just a 'tick fest' - but a marker does look to see how many relevant points you have made, then considers how you have strung them together to put your answer into a 'level'

Level 3:

The method would lead to the production of a valid outcome.

All key steps are identified and logically sequenced.
5 - 6 marks
Level 2:

The method would not necessarily lead to a valid outcome.

Most steps are identified, but the method is not fully logically sequenced.
3 - 4 marks
Level 1:

The method would not lead to a valid outcome.

Some relevant steps are identified, but links are not made clear.
1 - 2 marks
Level 0:

No relevant content
0 marks

 

Indicative content - some indicative content could be indicated within a labelled diagram:

place a glass block on a piece of paper

draw around the glass block

use the ray box to shine a ray of light through the glass block

mark the ray of light entering the glass block

mark the ray of light emerging from the glass block

join the points to show the path of the complete ray through the block

and draw a normal line (a line at 90 degrees to the surface)

use a protractor to measure the angle of incidence

use a protractor to measure the angle of refraction

use a ray box to shine a ray of light at a range of different angles (of incidence)

increase the angle of incidence in 10 degree intervals

from an angle of incidence of 10 degrees to an angle of incidence of 80 degrees

Methods involving mirrors and reflection score zero

 

[6 marks]

(b) Here is an incomplete graph of the results:

Complete the graph - using data from the table.

Label the axes.

Plot the remaining data.

All points plotted correctly got your two marks - one mark was awarded if 3 or 4 points were plotted correctly.

Tolerance of half a small square was allowed

Draw a line of best fit.

A smooth curved line of best fit was required - not a 'dot to dot' set of straight lines

[4 marks]

(Total 10 marks)