Question

In a double slit experiment the angular width of a fringe is found to be `0.2^(@)` on a screen placed I m away. The wavelength of light used in 600 nm. What will be the angular width of the fringe if the entire experimental apparatus is immersed in water ? Take refractive index of water to be `4//3`.

Answer 1

Here, `theta_(1) = 0.2^(@), D = 1mm lambda_(1) = 600 nm, theta_(2) = ?, mu = 4//3`
`(theta_(2))/(theta_(1)) = (lambda_(2))/(lambda_(1)) = (1)/(mu) = (3)/(4) theta_(2) = (3)/(4)theta_(1) = (3)/(4) xx 0.2^(@) = 0.15^(@)`