A Young's double-slit interference experiment is performed with monochromatic light. The separation between the slits is 0.48 mm. The interference pattern on the screen 3.7 m away shows the first maximum 5.1 mm from the center of the pattern. What is the wavelength of the light in nm

Wavelength of light used will be equal to 661 nm

Explanation:

We have given distance between slits d = 0.48 mm =

It is given interference pattern is 3.7 m away so D = 3.7 m

First maximum from the center is 5.1 mm

So

Distance of the first maximum from the center is equal to

So wavelength of light used will be equal to 661 nm

one "light year" is the distance that light travels, through vacuum, in one julian year.   that's 365.25 days, of 24 hours each.