Question

A uniform electric field $E = 2 \times 10^{3}NC^{- 1}$ is acting along the positive x – axis. The flux through the same square if the line normal to its plane makes a $60^{o}$angle with the x – axis is.

• A. 30 N $C^{- 1}m^{2}$
• B. 10 N $C^{- 1}m^{2}$
• C. 20 N $C^{- 1}m^{2}$
• D. 25 N $C^{- 1}m^{2}$

Answer 1

Answer: (B)

10 N $C^{- 1}m^{2}$

Answer 2

: When normal to the plane makes an angle of $60^{o}$with x –axis, then $\theta = 60^{o}$

$\varphi = ES\cos\theta = 2 \times 10^{3} \times 10^{- 2}\cos 60^{o}$

$= 20 \times \frac{1}{2} = 10NC^{- 1}m^{2}$