Question

Charges $2\mu C$ and $1\mu C$ are placed at corners $A$ and $B$ of square of side $5cm$ as shown in figure. The amount of work to be done against the electric field in moving a charge of $1.0\times {10}^{-6}C$ from $C$ to $D$ is :

• A. $0.045J$
• B. $0.053J$
• C. $0.017J$
• D. $0.03J$

Answer 1

The correct option is B $0.053J$

Work to be done against the electric field in electric field in moving a charge $=1.0\times {10}^{-6}C$

$F=\frac{1}{4\pi {ϵ}_0}\times \frac{q_1{q}_2}{r^2}$

$=9\times {10}^9\times \frac{2\times {10}^{-7}\times 3\times {10}^{-7}}{{(5\times {10}^{-2})}^2}$

$=2.16\times {10}^{-19}N$

$W=JF$

or, $J=\frac{W}{F}$

$E=\frac{F}{q}=\frac{2.16\times {10}^{-19}}{1.0\times {10}^{-6}}=0.053J$