Question

The diagram in Fig. shows an incident ray AO and the reflected ray OB from a plane mirror. The angle AOB is 30°. Draw normal on the plane mirror at the point O and find:

Answer 1

(i) the angle of incidence

(ii) the angle of reflection

ON is normal on the plane mirror at point O

ON is perpendicular on a plane mirror

Angle of incidence ∠i = ∠AON

and angle of reflection ∠r = ∠BON

Since, ∠i – ∠r

∠AOB = 30°

⇒ ∠AON + ∠BON = 30°

⇒∠i + ∠i – 30°

⇒ 2 ∠i = 30°

⇒ ∠i = 30 / 2 = 15°

∴ Angle of incidence = ∠i = 15°

and Angle of reflection ∠i = 15°