Question

For hearing the loudest ticking sound heard by the ear, find the angle x in the figure.

Answer 1

Incident line is making an angle of ${50}^o$ with reflecting surface.

The angle of incidence is measured from the normal

So angle of incidence $\angle i={90}^o-{50}^o={40}^o$

The directions in which the sound is incident and is reflected make equal angles with the normal to the reflecting surface at the point of incidence, and the three are in the same plane.

$\angle i=\angle r$

So Angle of reflection $\angle r=$ angle of incidence $\angle i={40}^o$
Hence, $\angle x={90}^o-{50}^o={40}^o$