Question

Green light of wavelength 5100 Å from a narrow slit is incident on a double slit. If the overall separation of 10 fringes on a screen 2 m away is 2 cm. Find the slit separation.

Answer 1

Data: λ = 5100 Å = 5.1 × 10⁻⁷ m, 10 W = 2 cm, D = 2 m

∴ W = `2/10` cm = 2 × 10⁻³ m

W = `(λD)/d`

∴ d = `(λD)/W`

= `(5.1 xx 10^-7 xx 2)/(2 xx 10^-3)`

= 5.1 × 10⁻⁴ m

= 0.51 mm

This is the slit-separation.