Outside the wireless charging coil is -. The wireless charging coil is an inductive coil that achieves wireless charging through electromagnetic induction. In the process of transmitting electrical energy, an alternating electric field will be generated inside the coil, and the alternating electric field will cause the flow of current, so as to achieve wireless charging.
According to the right-hand helix rule, the direction of the electric field outside the coil is perpendicular to the coil surface, and the direction is from the outside to the inside, so the electric field outside the coil points to the inside of the coil, that is, the negative pole. This ensures that the electrical energy can be efficiently transmitted to the receiving end for charging. Therefore, the outside of the wireless charging coil is negative.