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

When mirro is rotated by ` theta ` angle reflected ray will be rotated by ` 2 theta ` .

`(y)/(x)= 2 theta `
`theta=(y)/(2x)`