Question
Two slits are separated by a distance of 0.5 mm and illuminated with light of wavelength λ = 6000 Ao. If the screen is placed at 2.5 m from the slits. The distance of the third bright fringe from the centre will be
1.5 mm
3 mm
6 mm
9 mm
Solution
D.
9 mm
Distance of nth bright fringe from the centre,
xn =
where n = 0, ± 1,±2,.....
The third bright fringe width from the centre,
x3 =
= 9 × 10-3 m
x3 = 9 mm
