Science
Two mirrors meet at right angles. A ray of light is incident on one at an angle of 30° as shown in Fig. 13.19. Draw the reflected ray from the second mirror.
Answer
Let MM' and M'M'' be the two plane mirrors at right angles.
The reflected ray from the second mirror is shown in the figure below:
Given that the ray is incident on mirror MM' at 30°,
∴ ∠AOX = 30°
According to the law of reflection,
∠i = ∠r
∴ ∠XOO' = ∠AOX = 30°
As OX ⊥ MM' and O'X ⊥ M'M''
∴ OX ⊥ O'X
∴ ∠OXO' = 90°
In ΔOXO', by angle sum property.
∠XOO' + ∠OXO' + ∠XO'O = 180°
⇒ 30° + 90° + ∠XO'O = 180°
⇒ ∠XO'O = 180° - 90° - 30°
⇒ ∠XO'O = 60°
∴ Angle of incidence of the ray on M'M'' = 60°
∴ Angle of reflection of the ray from M'M'' = 60° [∵ ∠i = ∠r]
Related Questions
What is the angle of incidence of a ray if the reflected ray is at an angle of 90° to the incident ray?
How many images of a candle will be formed if it is placed between two parallel plane mirrors separated by 40 cm?
Boojho stands at A just on the side of a plane mirror, as shown in Fig. 13.20. Can he see himself in the mirror? Also, can he see the image of objects situated at P, Q and R?
(a) Find out the position of the image of an object situated at A in the plane mirror (Fig. 13.21).
(b) Can Paheli at B see this image?
(c) Can Boojho at C see this image?
(d) When Paheli moves from B to C, where does the image of A move?
