Question

There is an electric field $E$ in the x-direction. If the work done by the electric field in moving a charge of $0.2C$ through a distance of $2m$ along a line making an angle ${60}^{\circ }$ with the x-axis is $4J$, then what is the value of $E$?

• A. $\sqrt{3}N{C}^{-1}$
• B. $4N{C}^{-1}$
• C. $5N{C}^{-1}$
• D. $20N{C}^{-1}$

Answer 1

The correct option is D $20N{C}^{-1}$

$F=qE$
work will only be done in moving the charged particle in $x$ direction

work done in moving the charge in y-direction will be $0$
Work done , $W=\int \overrightarrow{F}.\overrightarrow{dr}$

$W=qE\times 2cos{60}^{\circ }$

or $4=0.2E\times 2\times \frac{1}{2}$

$⟹E=20N{C}^{-1}$