# GCSE level questions on light

Q2. The diagram shows the apparatus a student used to investigate the reflection of light by a plane mirror. The student drew four ray diagrams for each angle of incidence.

The student then carefully measured the angle of reflection from each diagram.

The following table gives the student's results.

 Angle of reflection Angle of incidence Test 1 Test 2 Test 3 Test 4 20° 19° 22° 20° 19° 30° 31° 28° 32° 30° 40° 42° 40° 43° 41° 50° 56° 49° 53° 46°

(a) For each angle of incidence, the angle of reflection has a range of values.

This is caused by an error. What type of error will have caused each angle of reflection to have a range of values?

[1 mark]

(b) Suggest what the student may have done during the investigation to cause each angle of reflection to have a range of values.

[1 mark]

(c) Estimate the uncertainty in the angle of reflection when the angle of incidence is 50°. Show how you determine your estimate.

[2 marks]

(d) The student concluded that for a plane mirror, the angle of incidence is equal to the angle of reflection. Explain whether you agree with this conclusion.