A potential difference of \( 100 \) V is maintained across a conductor having resistance \( 50\,\Omega \). The number of electrons passing through it in 2 s is
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → \( 2.5\times10^{19} \)
By Ohm’s law the current is \( I = V/R \); the charge that passes in time t is \( q = It \), and each electron carries \( e = 1.6\times10^{-19}\,\mathrm{C} \), so the number of electrons is \( n = q/e \).
\( I = \frac{V}{R} = \frac{100}{50} = 2\,\mathrm{A} \)
\( q = It = 2\times2 = 4\,\mathrm{C} \)
\( \displaystyle n = \frac{q}{e} = \frac{4}{1.6\times10^{-19}} = 2.5\times10^{19} \)