Question

In an electric field region, the electric potential varies along the $x$ axis as shown in the graph. The $x$ components of the electric field in the regions for the intervals $P Q$ and $Q R$ as marked in the graph, in $N/C$, are respectively:

• A. $5.0$ along negative $x$-direction and $20.0$ along positive $x$-direction
• B. $5.0$ along positive $x$-direction and $20.0$ along negative $x$-direction
• C. $5.0$ along negative $x$-direction and $20.0$ along negative $x$-direction
• D. $5.0$ along positive $x$-direction and $20.0$ along positive $x$-direction

Answer 1

Answer: (D)

$E_{P Q}=-\frac{d V_{P Q}}{X_{P Q}}=-\frac{\left(V_{Q}-V_{P}\right)}{X_{P Q}}$
$=\frac{-(0-5)}{1.0}=5 \,N / C$
and $ E_{Q R}=-\frac{(-10-0)}{0.5}=20 \,N / C$