Question

In Young’s double slit experiment, a laser light of 560 nm produces an interference pattern with consecutive bright fringes’ separation of 7.2 mm. Now another light is used to produce an interference pattern with consecutive bright fringes’ separation of 8.1 mm. The wavelength of the second light is ________ nm.

Answer 1

λ=560×10−9
B1=7.2×10−3
B2=8.1×10−3
$\frac{B_1}{B_2}=\frac{\lambda_1}{\lambda_2}$
⇒λ2=$\frac{560×10^{−9}×8.1×10^{−3}}{7.2×10^{−3}}$
=6.3×10−7 m
=630 nm