Question

In a biprism experiment, monochromatic light of wavelength (λ) is used. The distance between two coherent sources is kept constant. If the distance between slit and eyepiece (D) is varied as D₁, D₂, D₃, and D₄, the corresponding measured fringe widths are z₁, z₂, z₃, and z₄ then ______ 

Options

• `z_1sqrt(D_1) = z_2sqrt(D_2) = z_3sqrt(D_3) = z_4sqrt(D_4)`

• `z_1D_1^2 = z_2D_2^2 = z_3D_3^2 = z_4D_4^2`

• `z_1D_1 = z_2D_2 = z_3D_3 = z_4D_4`

• `z_1/D_1 = z_2/D_2 = z_3/D_3 = z_4/D_4`

Answer 1

In a biprism experiment, monochromatic light of wavelength (λ) is used. The distance between two coherent sources is kept constant. If the distance between slit and eyepiece (D) is varied as D₁, D₂, D₃, and D₄, the corresponding measured fringe widths are z₁, z₂, z₃, and z₄ then `underline(z_1/D_1 = z_2/D_2 = z_3/D_3 = z_4/D_4)`.

Explanation:

Fringe with Z = `(lambdaD)/d`

∴ `Z/D = lambda/d` = constant, as d is constant

∴ `z_1/D_1 = z_2/D_2 = z_3/D_3 = z_4/D_4`