A photon with initial frequency `10^(11)` Hz scatters off electron at rest. Its final frequency is `0.9 xx 10^(11)` Hz. The speed of scattered electron is close to: `(h = 6.63 xx 10^(-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. `30 ms^(-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) rArr (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(14615384)=3.8xx10^(3)~~ 4xx10^(-3) ms^(-1)`.