Question

A Michelson interferometer uses red light with a wavelength of $656.45nm$ from a hydrogen discharge lamp. How many bright-dark-bright fringe shifts are observed if mirror $M2$ is moved exactly $1cm$?

Short answer

Number of Bright-Dark-fringes shifts,$∆m=30500$

Step-by-step solution

Hydrogen lamp

A hydrogen lamp features a glass lamp enclosure with a radiation-emitting window that receives a body manufactures from a zirconium-cobalt alloy that forms a part of a hydride that is a reservoir for hydrogen or deuterium and allows controlled hydrogen or deuterium liberation from the reservoir.

Find Distance

The number $\Delta m$of passing fringes is calculated as follows:

localid="1650215643046" $\Delta m=\frac{\Delta L}{\lambda /2}$

$=\frac{2\Delta L}{\lambda }$

In our numerical example, we have

localid="1650215627172" $\Delta m=\frac{2\times 0.01m}{6.5645\times {10}^{-7}m}$

$=30500$