The number of waves passing through a specified issue during the interval of 1 second. The upper the frequency, the shorter the wavelength.???? ? ???? ?????? ??????? ?? ???? ???? ? ?? ???????? ?????? ??????? ?? ??? ? ?? ?????? ??? ????? ??? ???????? ?? ??????? ????? ??? ? ????? ??? ??? .?? ???? ?????? ????? ??? ?? ????? ????? ??????? ???? ???? ????