, , . . Rm F, , . . . Rm = l / mm0S, l S - , m - , m0 - . ( l, S, m) . . Rm . . . , : " " ( ), , . . . . . - , . . . ( -) (/), - (/). 1 / = 4p-10-9 / " 1,2566-10-8 /.

: