Question

A ray of light strikes a plane mirror PQ at an angle of incidence of 30 degree , is reflected from the plane mirror and then strikes a second plane mirror QR placed at right angles to the first mirror. The angle of reflection at the second mirror is:

Answer 1

aloha!

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first of all clear these terms out with me :)

◆ angle of reflection: it is the angle which a reflected ray forms with the normal.
◆ angle of incidence: it is the angle which an incident ray makes with the normal.
◆ normal: it is an imaginary line which is perpendicular to certain type of mirror.

now,

angle of incidence = angle of reflection. ----1

we know that an incident ray which strikes the first mirror I.e PQ at the angle of incidence 30°

also, by 1 we get that angle of reflection for the first case would be 30°

now the same reflected ray again in the form of incident ray makes an angle of incidence of 30° and gets reflected by the angle of 30°.

total reflection would have been: 30° + 30°i.e 60°

angle of reflection at the second mirror is 60°.


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hope it helps :)

Answer 2

Answer:

angle of incidence = angle of reflection. ----1

we know that an incident ray which strikes the first mirror I.e PQ at the angle of incidence 30°

also, by 1 we get that angle of reflection for the first case would be 30°

now the same reflected ray again in the form of incident ray makes an angle of incidence of 30° and gets reflected by the angle of 30°.

total reflection would have been: 30° + 30°i.e 60°

angle of reflection at the second mirror is 60°.