Angular width of the central maxima in the Fraunhofer diffraction for λ = 6000
Å is θ0. When the same slit is illuminated by another monochromatic light, the angular width decreases by 30%. The wavelength of this light is,

Question

Question

Answer 1

CONCEPT:

The angular width is written as;

Here we have θ is the angular width, λ is the wavelength and d is the distance.

CALCULATION:

Given: Wavelength, λ = 6000 Å

As we know,

----(1)

and When the same slit is illuminated by another monochromatic light, the angular width decreases.

----(2)

Now, on dividing the equation (1) and (2) we have;

⇒

⇒ λ' = 4200 Å

Hence, option 4) is the correct answer.

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