Question

A laser 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.

Answer 1

902 nm

Step-by-step explanation:

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

`y=(m\lambda D)/(a)`

where:

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

`\lambda` 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:

`a=1.55\cdot 10^(-4) m\\D = 2.75 m`

And also,

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

Solving the equation for
`\lambda`, we find the wavelength:

`\lambda = (ya)/(mD)=((0.048)(1.55\cdot 10^(-4)))/(3(2.75))=9.02\cdot 10^(-7) m = 902 nm`