Question

For a finite line charge, the net electric field at any point on equatorial line makes an angle of _______ with the axis of line charge.

• A. ${45}^{\circ }$
• B. ${60}^{\circ }$
• C. ${75}^{\circ }$
• D. ${90}^{\circ }$

Answer 1

The correct option is D ${90}^{\circ }$


On an equatorial line, the value of the component of net electric field in the direction parallel to the axis of line charge is zero.
$E_{||}=\frac{kQ}{Lr}(\cos \beta -\cos \alpha )$
Since $\alpha =\beta ={90}^{\circ }$, $E_{||}=0$
There is only electric field in the direction perpendicular to the axis of line charge.

Thus, its angle with the axis of line charge is ${90}^{\circ }$.