Given,
D = 1.15 m (distance of slots from
screen)
d = 0.100 mm
10^-4 m (distance between the two slits)
m = 1 (first order bright fringe)
xm = 4.2 cm
0.042 m (distance of first order bright fringe from centreline)
We know that,
xm = m* D λ/d (λ= wavelength)
0.042 = 1* 1.15 λ/10^-4
λ = (0.042 * 10^-4)/1.15
Therefore,
λ = 0.0365 * 10^-4
3.65 * 10^-6 m (approx)
