Light Waves
3 marks · EasyThe diagram below shows a ray of light entering a rectangular glass block from air.
Draw the normal at point F where the ray meets the glass block.
Show the path of the refracted ray inside the glass block.
Label the angle of incidence and the angle of refraction on your diagram.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) A straight line at 90° to the boundary at F. · must show normal drawn at F, 90° to boundary
(b) Ray bends towards the normal inside the glass block. · must show refracted ray inside block, bent to normal
(c) Angles on diagram: incidence in air, refraction in glass. Both shown and labelled. · must show angle of incidence and angle of refraction labelled
Common mistakes: refracted ray bending wrong way; normal missing or not at right angles; incorrectly labelled angles
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Draws normal at F, at 90° to the boundary.
B1 (b) · 1 mark · Draws refracted ray bent towards normal inside glass.
B1 (c) · 1 mark · Correctly labels the angle of incidence and angle of refraction.
Worked solution
a) Draw normal at F (perpendicular to the air-glass boundary). b) The refracted ray inside the glass bends towards the normal. c) Show and label both the angle of incidence (between incident ray and normal in air) and angle of refraction (between refracted ray and normal in glass).