A beam of light from a source L is incident normally on a plane mirror fixed at a certain distance x from the source. The beam is reflected back as a spot on a scale placed just above the source L. When the mirror is rotated through a small angle `theta` the spot of the light is found to move through a distance y on the scale. The angle `theta` is given by

Options

A. `(y)/(2x)`
B. `(y)/(x)`
C. `(x)/(2y)`
D. `(x)/(y)`

Answer

A

Explanation

According to the question L =Light source
When the light beams incidents normally on the plane mirro it is relected back to the point from which it was coming When the plane mirro is rated byv an angle `theta` the reflected ray or beam of light must raotate by angle `2theta` from refraction at plane surfacce theroy

From the figure `tan 2theta =(Bs)/(SO) =y/x`
If the angle is small `tan 2theta =2theta`
so, " "`2theta=y/xrArrtheta=(y)/(2x)`