waves

Question

Blue light of wavelength 465 nm is incident on a double slit where the slits are spaced 0.5 mm apart and are 0.05 mm wide.  The angle of diffraction that the fourth order antinodal line will appear is __

Answer 1

Wavelength of the Blue light λ is 465 nm = 465 * 10^-9 m

Distance between two slits d is 0.5 mm = 0.5 * 10^-3 m

Fourth order antinodal line m = 4

We know that Double slit interference Equation m λ = d sin θ

sin θ =  m λ / d

sin θ =  (4 * 465 * 10^-9) / (0.5 * 10^-3 )

sin θ =  3.72 * 10^-3

θ = 0.213°

Therefore angle of Diffraction is 0.213°.