The potential difference applied to an X-ray tube is 5 kV and the current through it is 3.2 mA. The number of electrons striking the target per second is

Options

(a) 5 x 10¹⁶
(b) 1 x 10¹⁷
(c) 4 x 10¹⁵
(d) 2 x 10¹⁶

Correct Answer:

2 x 10¹⁶

Explanation:

Let n = number of electrons striking per sec.

e = 1.6 × 10⁻¹⁹ = charge on each electron

Charge per second = n × 1.6 × 10⁻¹⁹

Current = n × 1.6 × 10⁻¹⁹

3.2 × 10⁻³ = n × 1.6 × 10⁻¹⁹

n = 3.2 × 10⁻³ / 1.6 × 10⁻¹⁹ = 2 × 10¹⁶