Chapter-6|Electromagnetic Induction (EMI)| NCERT 12th Physics:
Flux linkage of a closely wound coil is directly proportional to the current I i.e.
For a closely wound coil of N turns, the same magnetic flux is linked with all turns. The flux ΦB with the coil changes, each turn contributes to the induced EMF. Therefore, flux linked with the coil is equal to NΦB. In this case,
Total flux, NΦB∝I
The constant of proportionality in this relation is called inductance. Therefore, inductance is basically a measures of the ratio of the flux to the current.