In Young’s double slit experiment, the slits are separated by 0.28 mm and the screen is placed 1.4 m away. The distance between the central bright fringe and the fourth bright fringe is measured to be 1.2 cm, determine the wavelength of light used in the experiment.
Here slit width d=0.28mm = 0.28 x ${{10}^{-3}}$ m
Distance between slit and screen D = 1.4 m
y=1.2 cm = 1.2 x ${{10}^{-2}}$ m,n=4,λ = ?
For consecutive interference,
y=nλD/d or λ = yd/nD
= 1.2 x ${{10}^{-2}}$ x0.28 x ${{10}^{-3}}$/4 x 1.4
= 6 x ${{10}^{-7}}$ m