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CUET · PHYSICS · PYQ PAPER 2025

A parallel beam of monochromatic light of wavelength 900 nm passes through a long slit of width 0.4 mm. The angular divergence in which most of the light is diffracted, is:

  1. A \( 8.9 \times 10^{-3} \, \text{rad} \)
  2. B \( 7.2 \times 10^{-3} \, \text{rad} \)
  3. C \( 3.6 \times 10^{-3} \, \text{rad} \)
  4. D \( 4.5 \times 10^{-3} \, \text{rad} \)
Verified Solution

Answer & Solution

Correct Answer

(D) \( 4.5 \times 10^{-3} \, \text{rad} \)

Step-by-step Solution

Detailed explanation

\( \text{Angular divergence} = \frac{2\lambda}{a} \) \( = \frac{2 \times 900 \times 10^{-9} \, \text{m}}{0.4 \times 10^{-3} \, \text{m}} \) \( = 4.5 \times 10^{-3} \, \text{rad} \)