Question

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

• A. $2\times {10}^{16}$
  
• B. $5\times {10}^{16}$
  
• C. $1\times {10}^{16}$
  
• D. $4\times {10}^{16}$

Answer 1

The correct option is A

$2\times {10}^{16}$

Let 'n' be the number of electrons hitting the target.

Let 't' be the total time the X-ray tube was in working condition.
Therefore : $\frac{n}{t}=\frac{I}{e}=\frac{3.2\times {10}^{-3}}{-1.6\times {10}^{-19}}$
$=2\times {10}^{16}$......(We ignore the negative charge of an electron and only consider the magnitude to find the number of electrons)