The angular width of the central maximum in a single slit diffraction pattern is 60 ° . The width of the slit is 1 μm . The slit is illuminated by monochromatic plane waves. If another slit of the same width is made near it, Young's fringes can be observed on a screen placed at a distance 50 cm from the slits. If the observed fringe width is 1 cm , what is slit separation distance? (i.e., the distance between the centres of each slit.)

Question

The angular width of the central maximum in a single slit diffraction pattern is 60 ° . The width of the slit is 1 μm . The slit is illuminated by monochromatic plane waves. If another slit of the same width is made near it, Young's fringes can be observed on a screen placed at a distance 50 cm from the slits. If the observed fringe width is 1 cm , what is slit separation distance? (i.e., the distance between the centres of each slit.), 100 μm, 25 μm, 50 μm, 75 μm

MARKS App · Accepted Answer

In diffraction, d sin 30 ° = λ , λ = d 2 Young’s fringe width [ d ' - the separation between two slits] β = λ × D d ' ⇒ 10 - 2 = d 2 × 50 × 10 - 2 d ' ⇒ 10 - 2 = 10 - 6 × 50 × 10 - 2 2 × d ' ⇒ d ' = 25 μm .

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