Electric Charges and Fields - Result Question 33
33. There is an electric field $E$ in $x$-direction. If the work done on moving a charge of $0.2 C$ through a distance of $2 m$ along a line making an angle $60^{\circ}$ with $x$-axis is $4 J$, then what is the value of $E$ ?
[1995]
(a) $3 N / C$
(b) $4 N / C$
(c) $5 N / C$
(d) $20 N / C$
Topic 3: Electric Flux & Gauss’s Law
Show Answer
Answer:
Correct Answer: 33. (d)
Solution:
- (d) Charge $(q)=0.2 C$;
Distance $(d)=2 m$; Angle $\theta=60^{\circ}$ and work done $(W)=4 J$.
Work done in moving the charge $(W)$
$=F \cdot d \cos \theta=q E d \cos \theta$
$ \text{ or, } \begin{aligned} E & =\frac{W}{q d \cos \theta}=\frac{4}{0.2 \times 2 \times \cos 60^{\circ}}=\frac{4}{0.4 \times 0.5} \\ & =20 N / C . \end{aligned} $
