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GCSE questions on refraction and TIR

Q9. Anya used a ray box and glass block to investigate refraction of light.

Here is a diagram showing a ray of light entering the glass block.

(a) In the diagram, the angle of incidence is labelled with the letter i.

(i) Label the angle of refraction with the letter r.

(see diagram)

The correct angle had to be labelled - the letter 'r' on it's own was insufficient to get you the mark - you had to put in the curve around the angle.

[1 mark]

(ii) What is the value of the angle of incidence (Measure the angle of incidence on the diagram).

58o

[1 mark]

(iii) Complete the above diagram to show the path taken by the ray of light through the glass block and out into the air.

(see the diagram)

ray continuing in a straight line to the edge of the block

ray refracting away from the normal

both rays in the air should be parallel to each other

[3 marks]

(b) Anya repeated the measurement three times and calculated the mean to reduce the effect of errors. What type of error did she reduce?

She reduced random errors.

[1 mark]

(c) Here a the table of some of Anya's results.

It shows the values for the angles of incidence and the mean angles of refraction.

Angle of incidence in degrees
Mean angle of refraction in degrees
20
13
30
19
40
X
50
31

 

(i) For an angle of incidence of 40° the three measurements for the angle of refraction were: 23° 27° 25° Calculate the value of X

23 + 27 + 25 = 75

75 ÷ 3 = 25

X = 25

[1 mark]

(ii) Anya used the data in the table and correctly concluded that the angle of refraction is less than the angle of incidence used.

Choose words from the table below to complete this sentence.

equal to
greater than
less than

[1 mark]

(iii) Why is the Anya's conclusion only valid for angles of incidence between 20° and 50°?

There is no data/results outside of that range.

[1 mark]

(iv) Anya repeated the investigation using a transparent plastic block.

Why did she use a transparent block and not an opaque block?

Light would not pass through an opaque block, only through a transparent one.

[1 mark]

(v) Anya wanted to compare the refraction caused by the plastic with the refraction caused by the glass.

Which one of the following must she keep the same for both the plastic block and the glass block?

(Tick to indicate your choice)

The angles of incidence tested
The angles of refraction tested  
The number of results recorded  
The size of the two blocks  

[1 mark]

(Total 11 marks)