A wedged shaped air film having an angle of 40 seconds is illuminated by monochromatic light and fringes are observed vertically through a microscope. The distance measured between consecutive fringes is 0.12 cm. Calculate wavelength of light used.
β = 0.12 cmθ = 40 seconds = 1.9392 x 10-4 radians
`β = λ/(2θ)`
λ = β x 2θ= 0.12 x 2 x 1.9392 x 10-4= 4654 Ao
Wavelength of light used = 4654 Ao