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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:
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Solution
(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°
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