Question

Calculate the work done in taking a charge $-2\times 10^{-9}C$ from $A$ to $B$ via $C$ (in diagram)

• A. 0.2 joule
• B. 1.2 joule
• C. 2.2 joule
• D. Zero

Answer 1

Answer: (B)

$V_A=\frac{9\times 10^9\times 8\times 10^{-3}}{3\times 10^{-2}}=24\times 10^{8}V$
$V_B=\frac{9\times 10^9\times 8\times 10^{-3}}{4\times 10^{-2}}=18\times 10^{8}V$
$\Delta W=-2\times 10^{-9}\left(-6\times 10^8\right)$
$\Delta W=12\times 10^{-1}J$
$\Delta W=1.2J$