Question

Prachi while doing an experiment to verify the laws of reflection of sound , measured the angle between the incident and the reflected sound wave to be $120^0$ . The angle of reflection is?

Please answer the question with solution and detailed explanation. Thanks!

Answer 1

The angle of reflection is 60 degrees.

This is because angle of incidence = angle of reflection,

and the normal bisects the whole angle ie. angle of incidence + angle of reflection.

hence, if complete angle = 120 degree

angle of reflection = 60 degree.

Answer 2

See the attachment.
i = angle of incidence
r = angle of reflection

$The\ angle\ between\ incident\ ray\ and\ reflected\ ray =120^0 \\ \\ \angle i\ + \angle r=120^0\\ \\from\ laws\ of\ reflection\ \angle i\ = \angle r\\ \\so\ \angle i\ + \angle r=120^0\\\angle r\ + \angle r=120^0\\ 2\angle r=120^0\\ \angle r= \frac{120^0}{2}\\ \angle r=\boxed {60^0}$