Two slits in Young’s double slit experiment are 1.5 mm apart and the screen is placed at a distance of 1 m from the slits.

Question

Two slits in Young's double slit experiment are \(1.5 \mathrm{~mm}\) apart and the screen is placed at a distance of \(1 \mathrm{~m}\) from the slits. If the wavelength of light used is \(600 \times 10^{-9} \mathrm{~m}\) then the fringe separation is

(1) \( 4 \times 10^{-5} \mathrm{~m}\)

(2) \(9 \times 10^{-8} \mathrm{~m}\)

(3) \(4 \times 10^{-7} \mathrm{~m}\)

(4) \(4 \times 10^{-4} \mathrm{~m}\)

Answer 1

Correct option is : (4) \(4 \times 10^{-4} \mathrm{~m}\)

Fringe width = Fringe separation \((\beta)=\frac{\lambda D}{d}\)

\( \Rightarrow \beta=\frac{600 \times 10^{-9} \times 1}{1.5 \times 10^{-3}}=\frac{6 \times 10^{-7}}{1.5 \times 10^{-3}}=4 \times 10^{-4} \mathrm{~m} \)