Question

The electric current flowing through a given conductor varies with time as shown in the graph below. The number of free electrons which flow through a given cross-section of the conductor in the time interval \( 0 \leq t \leq 20 \, \text{s} \) is

• A. \( 3.125 \times 10^{19} \)
• B. \( 1.6 \times 10^{19} \)
• C. \( 6.25 \times 10^{18} \)
• D. \( 1.625 \times 10^{19} \)

Answer 1

The Correct Option is C

The charge $Q$ is given as:
\[ Q = ne = \text{area under } I-t \text{ graph} \] 

Substituting the values: \[ n = \frac{5000 \times 10^{-3}}{1.6 \times 10^{-19}} = 3.125 \times 10^{19} \]