question_answer

Two coherent plane light waves of equal amplitude makes a small angle a (« 1) with each other. They fall almost normally on a screen.

If \[\lambda \] the wavelength of light waves, the fringe width \[\Delta x\]of interference patterns of the two sets of waves on the screen is                                              [JEE ONLINE 19-05-2012]

A) \[\frac{2\lambda }{\alpha }\]

B) \[\frac{\lambda }{\alpha }\]

C) \[\frac{\lambda }{\left( 2\alpha  \right)}\]

D) \[\frac{\lambda }{\sqrt{\alpha }}\]

Correct Answer: C

Solution :

[c]