Question

An incident ray makes an angle of ${90}^{\circ }$with the mirror surface. The angle of reflection for this ray is:

• A. ${90}^{\circ }$
• B. $0^{\circ }$
• C. ${30}^{\circ }$
• D. ${45}^{\circ }$

Answer 1

Answer: (B)

$0^{\circ }$

Answer is B.
Angle of reflection is the angle that a reflected ray of light makes with the normal to the reflecting surface. The normal is an imaginary line which is perpendicular to the reflecting surface.
The angle of reflection is always equal to the the angle of incidence, which is the angle that the incoming ray, called incident ray makes with the normal.
The angle of incidence can be calculated from the angle incident rays makes the reflection surface as:
Angle of incidence = 90 - Angle made with reflecting surface
The angle with the reflecting surface, that is mirror, is given as 90 degrees.
Therefore:
Angle of incidence = 90 - 90 = 0 degrees
And
Angle of reflection = angle of incidence = 0 degrees.
Hence, the angle of reflection is 0 degrees.