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Physics · PYQ NEET UG 2017
हिन्दीA 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
Correct answer · Option 4
\( \frac{y}{2x} \)
Explanation
When a mirror is rotated by \( \theta \), the reflected ray rotates by \( 2\theta \). Therefore, \( y = 2x \cdot \theta \implies \theta = \frac{y}{2x} \).
