Refraction
3 marks · EasyState the Law of Reflection.
What is the angle of reflection when the angle of incidence is ?
Draw a labelled diagram to show a wave reflecting from a flat barrier. Include the normal, angle of incidence, and angle of reflection.
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(a) The angle of incidence equals the angle of reflection.
(b) 40 degrees
(c) — · must show barrier, normal, incident ray/wave, reflected ray/wave, correct labelling of 40 degrees
Common mistakes: Confusing incidence and reflection labels.
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Marking points
B1 (a) · 1 mark · States Law of Reflection: angle of incidence equals angle of reflection.
B1 (b) · 1 mark · Gives correct value for angle of reflection (40 degrees).
B1 (c) · 1 mark · Diagram contains a flat barrier, normal, incident and reflected rays, and correctly labelled angles of incidence and reflection (40°).
Worked solution
a) The angle of incidence equals the angle of reflection.
b) The angle of reflection is 40°.
c) [Draw a flat barrier, a normal at a point, an incident ray meeting at 40°, and a reflected ray leaving at 40° on the other side of the normal. Label all parts.]