A.将细铜丝拉直,用刻度尺测出细铜丝的长度L1;
B.用刻度尺测出铅笔杆上细铜丝线圈的宽度L2;
C.用细铜丝的长度L1除以细铜丝的圈数n,即得细铜丝的直径d;
D.将细铜丝紧密缠绕在铅笔杆上;
E.数出缠绕在铅笔杆上细铜丝的圈数n;