Consider \( I_1 \) and \( I_2 \) are the currents flowing simultaneously in two nearby coils 1 and 2, respectively. If \( L_1 \) = self-inductance of coil 1, \( M_{12} \) = mutual inductance of coil 1 with respect to coil 2, then the value of induced emf in coil 1 will be: