Question

A Narrow Slit illuminated by light of wave length
4900° Aº is placed at a distance of 3m from a
straight edge. If the distance between the straight
edge and screen is 6m calculate the distance
between the first and fourth band.​

Answer 1

Wavelength of light beam, λ

Distance of the screen from the slit, D=1m

For first minima, n=1

Distance between the slits is d

Distance of the first minimum from the centre of the screen can be obtained as, x=2.5mm=2.5×10

−3

Now, nλ=xd/D

⇒d=nλD/x=0.2mm

Therefore, the width of the slits is 0.2 mm.