JEE Main · 2021 · 16 Mar 2021 · Shift 1 · Wave Optics

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A fringe width of 6 mm was produced for two slits separated by 1 mm apart. The screen is placed 10 m away. The wavelength of light used is ' x ' nm .
The value of '

x

' to the nearest integer is ____

Answer: 600

Solution

The fringe width in a double-slit pattern is

β = \frac{λ D}{d}

. With

β = 6 \times 1 0^{- 3}

d = 1 \times 1 0^{- 3}

m and

D = 10

λ = \frac{β d}{D} = \frac{6 \times 1 0 ^{- 3} \times 1 0 ^{- 3}}{10} = 6 \times 1 0^{- 7} m

The wavelength of the light is 600 nm, so

x = 600

JEE Main · 2021 · 16 Mar 2021 · Shift 1 · Integer answer

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