Question

Two points $A$ and $B$ are located in diametrically opposite directions of a point charge of $+2 \, \mu C$ at distances $2 \,m$ and $1 \,m$ respectively from it. The potential difference between $A$ and $B$ is

• A. $3 \times 10^{3} \, V$
• B. $6 \times 10^{4} \, V$
• C. $-9 \times 10^{3} \, V$
• D. $-3 \times 10^{3} \, V$

Answer 1

Answer: (C)

Here, $q=2 \, \mu C=2\times10^{-6}\,C$,
$r_{A}=2m, r_{B}=1\,m$
$\therefore V_{A}-V_{B}=\frac{q}{4\pi\varepsilon_{0}} \left[\frac{1}{r_{A}}-\frac{1}{r_{B}}\right]$
$=2 \times10^{-6}\times9\times10^{9}\left[\frac{1}{2}-\frac{1}{1}\right]V $
$=-9 \times10^{3}\, V$