An X-ray tube, operated at a potential difference of 40 kV, produce heat at the rate of 720 W.Assuming 0.5% of the energy of incident electrons is converted into X-rays , calculate
(i)The number of electron per second striking the target
(ii)The velocity of the incident electrons .

Answer

(i) `1.1 xx 10^(17)`
(ii) `1.2 xx 10^(8) m//s`

Explanation

(i) Operating voltage `=40 kV, 0.5 %` energy for x ray
`:. 99.5/100xxnxxexxV=720`
`n=(720)/(1.6xx10^(-14)xx0.995xx40xx10^(3))=1.1xx10^(17)`
(ii) Velocity of incident `e^(-)implies 1/2 mv_(e)^(2)=eV`
`v_(e)=sqrt((2eV)/m)=sqrt((2xx1.6xx10^(19)xx40xx10^(3))/(9.1xx10^(-31)))`
`=1.2xx10^(8) m//s`