Question

The plastic rod of length $L$ has uniform charge density $\lambda$. Find the electric potential at a distance $r(>>L)$ far on the perpendicular bisector of the rod, to the right of it on the x-axis.

• A. $\frac{\lambda }{4\pi {ϵ}_0}ln\left(L/x\right)$
• B. $\frac{\lambda }{2\pi {ϵ}_0}\ln \left(x/L\right)$
• C. $\frac{\lambda }{4\pi {ϵ}_0}\ln \left(L/2x\right)$
• D. $0$

Answer 1

The correct option is D $0$

Length $=L$

Charge density $=\lambda$

$r>>L$

to the right of it on the axis $\lambda =\frac{Q}{L}$

This is the line charge density. Since $r>>L$. Then the $L$ becomes negligible hence to the right it is on the $x-$axis it becomes $0$.