Question

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

Answer 1

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

Step-by-step explanation:

y/2x

When the mirror is rotated by Ф angle reflected ray will be rotated by 2Ф

y/x  = 2Ф

Ф  y/2x