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 θ, the spot of the light is found to move through a distance y on the scale. The angle θ is given by

• A. $\frac {y}{2x}$
• B. $\frac {y}{x}$
• C. $\frac {x}{2y}$
• D. $\frac {x}{y}$

Answer 1

Answer: (A)

$\frac {y}{2x}$

Answer 2

The correct option is (A): $\frac {y}{2x}$.