(a) Potential at the mid-point of the line joining the two charges is                        or,                  Electric field at the mid-point O due to charge at BThus, the total electric field at the mid-point O is(b) Potential at the point C due to the two charges isElectric field at C due to charge at AElectric field at C due to charge at BIf the angle between E1 and E2 be θ, then      Thus, magnitude of resultant field at C isLet the field E makes angle α with the field E1.If field £ makes angle (3 with the direction BA, thenTherefore, angle of 69.4° is made by the electric field with the line joining the two charges. q2 to q1.