* Pass current $I_1$ through $S_1$
* Magnetic fields produced by $S_1$ = $\mu_0 N_1 I_1$
![image](https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/physics-class-12-unit-06-chapter-02-faradays-law-of-induction-mutual-and-self-inductance-l-2_4-hqm0dbe_7sa-337-1938.0.jpg)