question_answer

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 [NEET-2017]

A)  \[\frac{x}{y}\]       

B)  \[\frac{y}{2x}\]   

C)   \[\frac{y}{x}\]       

D)  \[\frac{x}{2y}\]

Correct Answer: B

Solution :

[b] When mirror is rotated by  angle reflected ray will be rotated by .