Question

Interference fringes were produced by two slits 0.25mm apart on a screen 150mm from the slits.If eight fringes occupy 2.62mm.What is the wavelength of the light producing the fringes?
(Please give the solution) 1st year physics Sindh text book board Chapter no 9 q.no 3

Answer 1

Hey mate,

● Answer -
λ = 546 nm

● Explanation -
# Given -
d = 0.25 mm = 0.25×10^-3 m
D = 150 mm = 0.15 m
y = 2.62 mm = 2.62×10^-3 m
λ = ?

# Solution -
Fringe width is calculated by -
W = y / 8
W = 2.62×10^-3 / 8
W = 0.3275×10^-3 m


In Young's double silb experiment, wavelength is given by -
λ = W × d / D
λ = 0.3275×10^-3 × 0.25×10^-3 / 0.15
λ = 5.46×10^-7
λ = 546 nm

Therefore, wavelength of light is 546 nm.