Alaser beam is used in young’s double slit experiment with slits separated by a distance 1.55*10-4 m. the screen is located at a distance of 2.75 m from the slits. the distance between the central bright fringe and the third order bright fringe is 0.048 m. find the length of laser light used in the experiment.

902 nm

Explanation:

We can solve the problem by using the formula for the diffraction from double slit:

where:

y is the distance of the m-th order diffraction maximum from the central fringe

is the wavelength of the light used

D is the distance of the screen from the slits

a is the distance between the slits

In this situation, we know:

And also,

y = 0.048 m for m = 3 (third order bright fringe)

Solving the equation for , we find the wavelength:

i think the answer is a, hope this : )