Question

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?

• A. 5 N / C
• B. 20 N/ C
• C. $ \sqrt 3 $ N / C
• D. 4 N / C

Answer 1

Answer: (B)

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 . d \, cos \, \theta = q E d \, cos \, \theta$
or, E = $ \frac{ W}{ qd \, cos \, \theta } = \frac{ 4}{ 0. 2 \times 2 \times cos \, 60^\circ } = \frac{ 4 }{ 0.4 \times 0. 5}$
= 20 N / C.