NEET Solved Paper 2017 Question 26
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
Options:
A) $ \frac{x}{y} $
B) $ \frac{y}{2x} $
C) $ \frac{y}{x} $
D) $ \frac{x}{2y} $
Show Answer
Answer:
Correct Answer: B
Solution:
When mirror is rotated by $ \theta $ angle reflected ray will be rotated by $ 2\theta . $ $ \frac{y}{x}=2\theta $ $ \theta =\frac{y}{2x} $
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