The secret is in the number of coils.

秘密在于线圈的数量。

Which means that the induced emf in a coil of wire is equal to the number of coils, times the change in magnetic flux over the change in time, all multiplied by a negative sign.

这意味着线圈中的感应电动势为 等于线圈数乘以磁通量随时间变化的变化，全部乘以负号。