Question

if the angle between the incident ray and reflected ray is 120 degrees, find the angle of reflection. Also state the law which governs your answer.​

Answer 1

Answer:

(For plane mirror) angle of reflection will be 30°

Explanation:

As angle of incident, angle of reflection and the normal lies on the same plane

And angle of incident = angle of reflection

(let angle of reflection =angle of incident=x)

2x+120°=180° (angles on a straight line)

2x=60°

x=30°

Hence angle of reflection=angle of incident = 30°

Answer 2

Answer:

Angle of reflection will be 60 degrees

Explanation:

Second law of reflection states that angle of incidence = angle of reflection, so if we add those two angles we will get the double of it.

So,

∠i + ∠r = 120

2∠r = 120 -------------- ∠i = ∠r

∴ ∠r = 60