Answer:
Wavelength of light used will be equal to 661 nm
Step-by-step 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