Question

What is the angle of incidence of a ray if the reflected ray is at an angle of 90 to the incident ray

Answer 1

→ Angle of incidence

r → Angle of reflection

i + r = 90 (Given) ——— 1

Let i = x

∵ i = r , r = x

By substituting i and r as x in equation 1 we get ,

x + x = 90

2x = 90

x = 45

∴ Angle of reflection = r = x = 45

Answer 2

If the reflected ray is at the angle of 90o to the incident ray, then the angle of incidence is 45o. According to the law of reflection, the angle of incidence and the angle of reflection are equal. Therefore, the angle of incidence and the angle of reflection both are 90/2=45o.