Question

Two slits separated by 0.10 mm are illuminated with green light (l = 540 nm). calculate the distance (in cm) from the central bright-region to the fifth bright band if the screen is 1.0 m away.

Answer 1

Applying the relation for diffraction;
d Sin Ф = m*wavelength

Where, Ф = angle, Sin Ф = y/1, y = distance from central bright region, m = 5 (for fifth bright band), d = distance of separation = 0.10 mm = 0.0001 m

Substituting,
0.0001*(y/1) = 5*540*10^-9
y = (5*540*10^-9)/0.0001 = 0.027 m = 0.027*100 cm = 2.7 cm