Please ans this. Please ans this. A spark passes in air when potential gradient at the surfaCe of charged metal is 3Mv/m. Find the diameter of the metal sphere, which can be charged to a potential of 1.5 MV before sparking into the air. Share with your friends Share 1 Sakshi Gupta answered this Dear student, Potential gradient represents electric field. So we have. Hope this helps. Regards 4 View Full Answer