Question

Through what angle a mirror is rotated about an axis passing through the point of incidence and in the plane of mirror so that the reflected ray is rotated through an angle of 40°?
O 40°
O 30°
O 20°
O 10°​

Answer 1

Answer:

Complete answer:

Thus, for a fixed incident ray, the reflection angle is twice the angle through which the mirror has rotated. When a plane mirror is rotated at an angle θ, the reflected ray rotates through the angle 2θ°

Answer 2

Concept: The ray of light falling on the surface of plane mirror is called the incident ray.

The incident ray bouncing back in the same medium after striking the reflecting surface of the mirror is called reflected ray.

Given: The reflected ray is rotated through an angle of 40°

Find: Calculate an angle by which mirror is rotated.

Solution: When a plane mirror is rotated through an angle θ, the angle turned by the reflected ray will be 2θ.

Therefore, angle of reflected ray =2θ

                                                  40°=2θ

                                                     θ= 40°/2

                                                     θ=20°

So, the mirror is rotated through an angle is 20°.

Final answer: c. 20°.

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