A ray of light strikes a plane mirror PQ at an angle of incidence of 30∘, 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 :
(a) 30∘ (b) 45∘ (c) 60∘ (d) 90∘ Draw a ray-diagram to illustrate your answer.
A ray of light strikes a plane mirror PQ at an angle of incidence of 30∘, 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 :
(a) 30∘ (b) 45∘ (c) 60∘ (d) 90∘ Draw a ray-diagram to illustrate your answer.
We know,
The angle of incidence = Angle of reflection. ----1
we know that an incident ray that strikes the first mirror I.e PQ at the angle of incidence of 30°
Now from equation 1, we get that angle of reflection for the first case would be 30°
Now the same reflected ray again in the form of an 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°
The angle of reflection at the second mirror is 60°.
Diagram for the given situation is -
We know,
The angle of incidence = Angle of reflection. ----1
we know that an incident ray that strikes the first mirror I.e PQ at the angle of incidence of 30°
Now from equation 1, we get that angle of reflection for the first case would be 30°
Now the same reflected ray again in the form of an 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°
The angle of reflection at the second mirror is 60°.
Diagram for the given situation is -
