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Question
Heat at the rate of 200 W is produced in an X-ray tube operating at 20 kV. Find the current in the circuit. Assume that only a small fraction of the kinetic energy of electrons is converted into X-rays.
Solution
Given:-
Heat produced/second = Power (P) = 200 W
Potential in the X ray tube, V = 20 kV
We know
Power, P = VI
Here, V = potential difference
I = current
But `l = (n e)/t`
Where, e = charge on electron
t = time
n = no of electrons
`therefore P = (n eV)/t`
`⇒ 200 = (n eV)/t`
`⇒ (n e"/"t)V = 200`
`⇒ I = 200/V`
`⇒ I = 200/(20 xx 10^3) = 10 "mA"`
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