Hyperfine effects on ESR in metals we suppose that the electron spin of a conduction electron in a metal sees an effective magnetic field from the hyperfine interaction of the electron spin with the nuclear spin. Let the z component of the field seen, by the conduction electron be written where I^z_f equally likely to be ? ?.?

(a) Show that (B²_t) = (a/2N)³N.?

(b) Show that (B^*_i = 3(a/2N) ⁴N², for N >> 1.

B B. - (*) ;