Question

A charge Q is uniformly distributed over a rod of length l. Consider a hypothetical cube of edge l with the centre of the cube at one end of the rod.Find the minimum possible flux of the electric field through the entire surface of the cube.

Answer 1

Given length of the rod=edge of cube =l

Portion of rod inside the cube =$\frac{l}{2}$

Total charge=Q

Linear charge density =$\frac{Q}{l_{{\in }_0}}$ of rod

We know flux =charged enclosed in the rod inside the cube =$\frac{l}{2}\times \frac{Q}{l{\in }_0}=\frac{Q}{2{\in }_0}$