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 $PQ$ and $QR$ 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)

$E_{PQ}=-\frac{d{V}_{PQ}}{X_{PQ}}=-\frac{\left(V_Q-V_P\right)}{X_{PQ}}$
$=\frac{-(0-5)}{1.0}=5N/C$
and $E_{QR}=-\frac{(-10-0)}{0.5}=20N/C$