Question

A Michelson interferometer operating at a 400 nm wavelength has a 3.95-cm-long glass cell in one arm. To begin, the air is pumped out of the cell and mirror M2 is adjusted to produce a bright spot at the center of the interference pattern. Then a valve is opened and air is slowly admitted into the cell. The index of refraction of air at 1.00 atmatm pressure is 1.00028.

Required:
How many bright-dark-bright fringe shifts are observed as the cell fills with air?

Answer 1

55.3

Step-by-step explanation:

The computation of the number of bright-dark-bright fringe shifts observed is shown below:

`\triangle m = (2d)/(\lambda) (n - 1)`

where

d =
`3.95 * 10^(-2)m`

`\lambda = 400 * 10^(-9)m`

n = 1.00028

Now placing these values to the above formula

So, the number of bright-dark-bright fringe shifts observed is

`= (2 *3.95 * 10^(-2)m)/(400 * 10^(-9)m) (1.00028 - 1)`

= 55.3

We simply applied the above formula so that the number of bright dark bright fringe shifts could come