Question

A beam of monochromatic light with a wavelength of 660 nm is directed at a double slit. Consider the five fringes labeled in the drawing, including the central maximum that is labeled "B." Which one of these fringes is 330 nm closer to one slit than it is to the other slit?

Answer 1

Answer:

A

Explanation:

A is the dark fringe and rest B, C, D and E are bright fringes. Destructive interference takes place for dark fringe formation. For destructive interference, the fringe width is half-integral multiple of wavelength. For constructive interference, the fringe width is integral multiple of wavelength.

A is the first dark fringe from the central fringe at

$\frac{n}{2}\lambda \\n =1 \\\frac{660nm}{2} = 330 nm$