??????? ?????? ??????? ????? ??? ??? ???????? ????? ????? ???? ?? ?????? ??? ??????? ??????? ??????? ???????? ?????? ???? ??????? ?? ?????? ???????.???? ????? ????? ??????????? ??????? ?????????? ?? ??? ??????? ?????????? ????? ??????? ?? ??????.Because of eddy currents induced during the steel, a sign is detected when steel is current. The reality