A student investigates the light reflected from a plane mirror.

1. (a)Fig. 2.1 shows a straight line AB.
2. (a)(i)Draw a line from point A at an angle of 30° in an anticlockwise direction from AB. This line should be more than 10cm long. Label the end of the line as point C.[1]
3. (a)(ii)Mark a point D on the line AB, 4.0 cm from point A. Draw a line perpendicular to AB through point D. This line must also pass through the line AC that you have drawn in part (a)(i). Label, with an E, the point where the line through point D passes through AC.[1]
4. (b)The student: • places a plane mirror along the line AC with the reflective surface facing point B • arranges an illuminated slit so that a ray of light passes along the line DE. The ray reflects from the mirror.
5. (b)(i)Draw a normal to line AC at point E.[1]
6. (b)(ii)Label the angle between DE and the normal you have drawn with a θ. Measure and record angle θ. θ =[1]
7. (b)(iii)The student: • marks two points P₁ and P2 on the reflected line • removes the mirror and draws the reflected line through points P₁ and P2. Describe how points P₁ and P₂ are chosen to give as accurate a reflected line as possible.[1]
8. (c)The student repeats the procedure with a ray of light striking the mirror at a different angle.
9. (c)(i)Fig. 2.2 shows a second line, labelled A'B'. On Fig. 2.2, draw a line from point A' at an angle of 60° in an anticlockwise direction from line A'B'. The line should be more than 10 cm long. Label the end of the line with a C'.[1]
10. (c)(ii)Mark a point D' on the line A'B', 4.0 cm from point A'. Draw a line perpendicular to A'B' through point D'. This line must also pass through the line A'C'. Label the point where the line through point D' passes through A'C' with an E'. Draw a normal to line A'C' at point E'.[1]
11. (c)(iii)Label the angle between D'E' and the normal you have drawn with an α. Explain one practical precaution that you take to ensure that the normal is accurately drawn.[1]
12. (c)(iv)Measure and record angle α. α =[1]
13. (d)Theory suggests that: α = 2θ. State whether your results support this theory. Give a reason for your answer.[1]

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