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Question
The electric current in an X-ray tube (from the target to the filament) operating at 40 kV is 10 mA. Assume that on an average, 1% of the total kinetic energy of the electron hitting hte target are converted into X-rays.
(a) What is the total power emitted as X-rays and (b) how much heat is produced in the target every second?
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Solution
Given :
V = 30 KV
i = 10mA
1% of TKE (total kinetic energy) = X-ray
i = ne
or `n = (10^-2)/(1.6 xx 10^-19)`
= `0.625 xx 10^17` (number of electrons)
KE of one electron = eV
= `1.6 xx 10^-19 xx 40 xx 10^3`
= `6.4 xx 10^-15 "J"`
`"T"_("KE") = 0.625 xx 6.4 xx 10^17 xx 10^-15`
= `4 xx 10^2 "J"`
(b) Heat produced in target per second = 400 − 4 = 396 J
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