Question

You find an unmarked blue laser on your way to physics class. When you get to class you realize you can determine the wavelength of the laser by doing a double slit experiment. Shining the laser through a double slit with a slit separation of 0.329 mm on the wall 2.20 m away the first bright fringe is 2.90 mm from the center of the pattern. What is the wavelength

Answer 1

Explanation:

We have,

Slit separation, d = 0.329 mm

Distance between slit and screen, D = 2.20 m

The first bright fringe is formed at a distance off 2.9 mm from the center of the pattern. We need to find the wavelength.

For double slit experiment, the fringe width is given by :

$\beta=\dfrac{D\lambda}{d}$

$\lambda$ is wavelength

$\lambda=\dfrac{\beta d}{D}\\\\\lambda=\dfrac{2.9\times 10^{-3}\times 0.329\times 10^{-3}}{2.2}\\\\\lambda=4.33\times 10^{-7}\ m\\\\\lambda=433\ nm$

So, wavelength is 433 nm.