Answer:
Explanation:
slit separation d = .15 mm
screen distance D = 1.4 m
wavelength of light used λ= 643 x 10⁻⁹ m
position of n th bright fringe x
x = n x λ D / d
1.8 x 10⁻² = n x 643 x 10⁻⁹ x 1.4 / .15 x 10⁻³
1.8 x 10⁻² = n x 6 x 10⁻³
n = 3
So 3 rd bright fringe will be formed at a point 1.8 cm from the central bright fringe .
