Velocity of an electron revolving in a certain orbit of H-atom is `(1)/(275)` tiems the velocity of light. Find the orbit in which the electron is revolving.

Explanation

Let the electron is revolving in the n-th orbit,
The velocity of the electron in the n-th orbit, `V_(n)=(2piZe^(2))/(nh)`
`=(2xx3.14xx(4.8xx10^(-10))^(2))/(nxx6.626xx10^(-27))" "[becauseZ=1" "e=4.8xx10^(-10)"esu "h=6.626xx10^(-27)erg*s]`
`=(2.18xx10^(8))/(n)cm*s^(-1)`
Given, velocity of revolution of the-electron
`=(1)/(275)xx(3xx10^(10))cm*s^(-1)=1.09xx10^(8)cm*s^(-1)`
`therefore (2.18xx10^(8))/(n)=1.09xx10^(8)`
or, `n=(2.18xx10^(8))/(1.09xx10^(8))=2`
`therefore`The electron is revolving in the 2nd orbit of H-atom.