A photon with initial frquency `10^(11) `Hz scatters off an electron at rest. Its final frequency is `0.9xx10^(11)Hz`. The speed of scattered electron is close to :
`(h=6.63xx10^(-34)Js,m_(e)=9.1xx10^(-31)kg)`

Options

A. `4xx10^(3)ms^(-1)`
B. `3xx10^(2)ms^(-1)`
C. `2xx10^(6)ms^(-1)`
D. `30ms^(-1)`

Answer

A

Explanation

Initial energy of photon
=Energy of photon after scattering +K.E. of scattered electron
`hv_(1)=hv_(2)+(1)/(2)mv^(2)`
`(1)/(2)mv^(2)=h(v_(1)-v_(2))`
`v^(2)=(2h(v_(1)-v_(2)))/(m)`
`=(2xx6.63xx10^(-34)(10^(11)-0.9xx10^(11)))/(9.1xx10^(-31))`
`v=sqrt(14571428)=3.8xx10^(3)~~4xx10^(3)ms^(-1)`