2. a) Outer sphere radius of a concentric spherical electrode system is given to be r2 = 15 cm. Determine the maximum voltage that can safely be applied to the system if the dielectric strength of the insulation is Ed=30 kV/cm. b) Determine the inner radius of the system in order to apply U=100 kV. c) Evaluate the system from the point of discharge phenomena (will there be a discharge, if so the type) for the inner radiuses of r₁'=2 cm, r₁"= 7 cm and r₁""= 14 cm.