Question

Two plane mirrors are inclined with each other at an angle of 50 degree. A light ray incident upon mirror 1, as shown is reflected from mirror 2 at an angle

1) 10 degree. 2) 20 degree

3) 80 degree. 4) 40 degree

Answer 1

Given: Two plane mirrors are inclined with each other at an angle of 50°, A light ray incident at angle 50° with plane.

To find: Ray reflected from mirror 2 at angle?

Solution:

• As we have given that ray incident at 50° with plane, this means the angle with the perpendicular will be 40°.

• Now, when the ray will reflect, it will follow the first law of reflection, which states that  when a ray of light reflects off a surface, the angle of incidence is equal to the angle of reflection.

• So angle of reflection with base will be 50°.

• Now, after the ray strikes the 2nd mirror, a triangle forms where two angles are 50° each. so the remaining angle will be 80°.

• Now, angle of incidence for mirror 2 is 80°, with respect to 2nd mirror, so the rest angle will be 10°.

Answer:

          So angle of reflection is 10°, with respect to perpendicular and 80° with respect to the plane of 2nd mirror.