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A monochromatic light source S of wavele...

A monochromatic light source S of wavelength 440 nm is placed slightly above a plane mirror M as shown . Image of S in M can be used as a virtual source to produce interference fringes on the screen. The distance of source S from O is 20.0 cm, and the distance of screen from O is `100.0` cm (figure is not to scale). If the angle `theta = 0.50 xx10^(-3)` radians, the width of the interference fringes observed on the screen is –

A

`2.20` mm

B

2.64 mm

C

`1.10` mm

D

`0.55` mm

Text Solution

Verified by Experts

The correct Answer is:
B
Here D = (100 + 20 cos `theta`) d = 40 sin `theta , lambda` = 440 nm
`beta = (lambda D)/(d) = (440 xx 10^(-6) xx 120 xx 10^(2))/(2 xx 10^(-2) xx 10^(2) ) = 264 xx 10^(-2)`
`rArr 2.64` mm.
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