WAEC - Physics (2000 - No. 25)
In the diagram above, an incident ray AY makes an angle of 30o with the normal XY. If the mirror is rotated anticlockwise about Y through an angle of 20o, while AY is fixed, what angle will the reflected ray now make with the incident ray?
70o
80o
100o
120o
Förklaring
The reflected ray will rotate through angle 2 x 20º = 40º
The reflected ray will now make angle 30º + 30º + 40º = 100º with the incident ray(30º + 30º since i = r)