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A slit of width 1 × 10⁻⁵ m is illuminated by light of wavelength 500 nm. The angular position of the first minimum (in radians, small angle) is approximately:

A0.05 rad
B0.005 rad (= 500 × 10⁻⁹ / 1 × 10⁻⁵)
C0.5 rad
D0.0005 rad
Answer & Solution
Correct answer: B. 0.005 rad (= 500 × 10⁻⁹ / 1 × 10⁻⁵)
First minimum: sin θ ≈ θ = λ/a = (500 × 10⁻⁹) / (1 × 10⁻⁵) = **0.05** — wait, 5 × 10⁻². Let me recompute: 5 × 10⁻⁷ / 1 × 10⁻⁵ = 5 × 10⁻² = **0.05 rad ≈ 2.86°**. So A is correct.
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