Question

Using Young’s double slit experiment, a monochromatic light of wavelength 5000Å produces fringes of fringe width 0.5 mm. If another monochromatic light of wavelength 6000Å is used and the separation between the slits is doubled, then the new fringe width will be ______.

Options

• 0.5 mm

• 1.0 mm

• 0.6 mm

• 0.3 mm

Answer 1

Using Young’s double slit experiment, a monochromatic light of wavelength 5000Å produces fringes of fringe width 0.5 mm. If another monochromatic light of wavelength 6000Å is used and the separation between the slits is doubled, then the new fringe width will be 0.3 mm.

Explanation:

As, β = `(lambda"D")/"d"`

Case 1: 0.5 mm = `(5000Å xx "D")/"d"_1`     ...(1)

Case 2: β₂ = `(6000Å xx "D")/(2"d"_1)`     ...(2)

Dividing Eq. (1) by (2), we get

`0.5/beta_2 = 5000/6000xx(2"d"_1)/"d"_1`

β₂ = `3/10`

= 0.3 mm