Question

Two points $P$ and $Q$ are maintained at the potentials of $10\,V$ and $-4\,V$ respectively. The work done in moving $100$ electrons from $P$ to $Q$ is

• A. $−19 ×10^{−17}\, J$
• B. $9.60 ×10^{−17}\, J$
• C. $−2.24 ×10^{−16}\, J$
• D. $2.24 ×10^{−16}\, J$

Answer 1

Answer: (D)

$W = QdV = Q\left(V_{q} - V_{p}\right) = -100 × \left(1.6 × 10^{-19}\right) × \left(- 4 - 10\right)$
$=+ 100 × 1.6 × 10^{-19} × 14 = +2.24 10^{-16}\, J.$