At a certain distance from a point charge, the potential and electric-field magnitude due to that charge are 4.98 V and 16.2 V/m, respectively. (Take V = 0 at infinity.) (a) What is the distance to the point charge? (b) What is the magnitude of the charge? (c) Is the electric field directed toward or away from the point charge?

Introduction We have to calculate the charge and the distance from the given electric field and potential at a point. Then we have to discuss whether the electric fields are going out or coming in. Step 1 (a) The potential due to a point charge q at a distance r is given by ...........(1) And the electric field is given by .......(2) Now dividing equation (1) by (2) we have