Question

The angle between an incident ray and the plane mirror is 30°. The total angle between the incident ray and reflected ray will be:

(a) 30°
(b) 60°
(c) 90°
(d) 120°

Answer 1

(b) 120^o
Since, angle of incidence = 90^o - angle between plane mirror and incident ray = 90^o - 30^o = 60^o
and according to first law of reflection, angle of incidence = angle of reflection = 60^o
Total angle between incident ray and reflected ray = 60^o + 60^o = 120^{o .}