A single slit located effectively at infinity in front of a lens of focal length `1 m`, and it is illuminated normally with light of wavelength `600 nm`. The first minimum on either side of central maximum are separated by `4 mm`. Width of the slit is

Options

A. `0.1 mm`
B. `0.2 mm`
C. `0.3 mm`
D. `0.4 mm`

Answer

C

Explanation

Here, `f = 1 m, lambda = 600 nm = 6 xx 10^(-7)m`
`n = 1, 2 x = 4 mm = 4 xx 10^(-3)m, a = ?`
As `x = (f lambda)/(a) :. a = (f lambda)/(x) = (1 xx 6 xx 10^(-7))/(2 xx 10^(-3))`
`= 3 xx 10^(-4)m = 0.3 mm`