Question

Electron guns are used in X-ray tubes. The electrons are accelerated through a relatively large voltage and directed onto a metal target, producing X-rays. (a) How many electrons per second strike the target if the current is 0.500 mA? (b) What charge strikes the target in 0.750 s?

Answer 1

Answer:

(a) Number of electrons per second strike the target is 3.125 x 10¹⁵.

(b) Charge that strikes the target in 0.750 s is 3.75 x 10⁻⁴ C .

Explanation:

(a) Let n be the number of electrons per second strike the target. We know that current (I) is given by the relation :

I = n x e

Here e is charge of electron.

Substitute 0.500 x 10⁻³ A for I and 1.6 x 10⁻¹⁹ C for e in the above equation.

0.500 x 10⁻³ = n x 1.6 x 10⁻¹⁹

n = 3.125 x 10¹⁵

(b) Let q be the charge that strikes the target. We know that :

q = I x t

Here I is current and t is time.

Substitute 0.500 x 10⁻³ A for I and 0.750 s for t in the above equation,

q = 0.500 x 10⁻³ x 0.750

q = 3.75 x 10⁻⁴ C