A point charge 4 is situated at a distance r on axis from one end of a thin conducting rod of length L having a charge Q (Uniformly distributed along its length). "The magnitude of electric force between the two is ________.

Answer

`1/(4pi in_(0))(qQ)/(d(d+L))`

Explanation

We consider an element of thickness dx at a distance x from q

Force on `q=int1/(4pi in_(0))xx(dQ.q)/x^(2)`
Where `dQ=Q/L dx` then, `F=(KQq)/(L) underset(d)overset(d+L)(int)(dx)/x^(2)=(KQq)/(d(d+L))`