A circular plane sheet of radius $10 cm$ is placed in a uniform electric field of $5\times {10}^5 N C^{-1}$, making an angle of ${60}^{°}$ with the field. The electric flux through the sheet is

Here, $r=10cm= 0.1 m, E=5\times {10}^5 N C^{-1}$

As the angle between the plane sheet and the electric field is ${60}^{°}$, angle made by the normal to the plane sheet and the electric field is $\theta ={90}^{°}-{60}^{°}={30}^{°}$

$$\begin{gathered} {\varphi }_E=ES \cos \theta =E\times \pi r^2\cos \theta \\ = 5 x {10}^5 x 3.14 x {(0.1)}^2 \cos {30}^{°} = 1.36 x {10}^4 N m^2 C^{-1} \end{gathered}$$