A slit of width a is illuminated by white light. The first minimum for red light λ = 6500 Å will fall at θ = 30 ° , when a is

Question

A slit of width a is illuminated by white light. The first minimum for red light λ = 6500 Å will fall at θ = 30 ° , when a is, 3250 Å, 6.5 × 1 0 - 4 c m, 1.3 μ m, 2.6 × 1 0 - 4 c m

MARKS App · Accepted Answer

sin ⁡ θ = λ a ⇒ sin ⁡ 30 ° = 6500 a Å ∴ 1 2 = 6500 a Å ∴ a = 2 × 6500 Å = 2 × 6500 × 10 - 10 m ∴ a = 1 .3 × 10 - 6 m

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