An electron in `H` atom makes a transition from `n = 3` to `n = 1`. The recoil momentum of the `H` atom will be

Options

A. `6.45 xx 10^(-27) Ns`
B. `6.8 xx 10^(-27) Ns`
C. `6.45 xx 10^(-24) Ns`
D. `6.8 xx 10^(-24) Ns`

Answer

A

Explanation

Recoil momentum `= (DeltaE)/(c )`
`DeltaE =- (13.6)/(9)-(-(13.6)/(1))`
`=13.6 - (13.6)/(9)`
`= (8xx13.6)/(9)eV = 12.09eV`.
`(DeltaE)/(c ) = (12.09xx1.6xx10^(-10))/(3xx10^(8))Ns`
`= 6.45xx10^(-27) Ns`