Question

Two slits, 4 mm apart, are illuminated by light of wavelength 6000 Å. What will be the fringe width on a screen placed 2m from the slits(a) 0.12 mm(b) 0.3 mm(c) 3.0 mm(d) 4.0 mm

Answer 1

Correct answer is b 0.3 mm

By using simple formula of fringe width

Answer 2

Answer:

Explanation:

Number of slits = 2 (Given)

Distance between them = 4mm (Given)

Wavelength of the slits =  6000 Å (Given)

Distance of the screen from width = 2m (Given)

Thus, according to the young's double slit formula -

β  =  λD / d ( where β is the bandwidth and d is the distance between two consecutive dark bands )

= 6000 × 10`10 × 2 / 4 × 10`3

= 3 × 10`4 m

= 0.3

Thus, the fringe width on a screen placed 2m from the slits is 0.3m