Question

With respect to a point P at a distance of 50cm, and wavelength of light 6000 A, find the number of zones observed from a circular hole of radius 1mm​

Answer 1

Explanation:

Fringe width is given by β=

d

λD

In the first case, λ

1

=6000 A

∘

=6000×10

−10

m

β

1

=6 mm=0.006 m

∴0.006=6000×10

−10

d

D

....(1)

In the second case, the distance between the slits and the screen is

2

D

,β

2

=4 mm=0.004 m

∴0.004=λ

2

×

d

2

D

....(2)

Directing equations (2) by (1) we get

0.006

0.004

=

2×6000×10

−10

λ

2

λ

2

=

0.006

0.004×2×6000×10

−10

λ

2

=

0.006

48×10

−10

λ

2

=8000×10

−10

λ

2

=8000 A

∘

.