Question

The network shown in the figure is a part of a complete circuit. If at a certain instant the current $i$ is $5\, A$ and is decreasing at the rate of $10^{3} A / s$, then $V_{B}-V_{A}$ is

• A. 5 V
• B. 10 V
• C. 15 V
• D. 20 V

Answer 1

Answer: (C)

By using Kirchhoff's voltage law,

$V_{A}-i R+E-L \frac{d i}{d t}=V_{B}$
$\Rightarrow V_{B}-V_{A}=-5 \times 1+15$
$-5 \times 10^{-3} \times\left(-10^{3}\right)=15\, V$