What do you understand by self-inductance of a coil? Given its physical singificance.

Explanation

i. When a circuit is switched on, the increasing current induces an emf which opposes the growth of current in a circuit (Figure (a)). Likewise, when circuit is broken, the reverse direction. This emf now opposes the decay of current (Figure (b)).

ii. Thus, inductance of the coil opposes any change in current and tries to maintain the original state.
iii. When the current i changes with time, an of electromagnetic induction, this self-induced emf is given by
`epsilon=(d(NPhi_(B)))/(dt)=-(d(Li))/(dt)" "...(1)`
`("using equation 1")`
`thereforeepsilon=-L(di)/(dt)(or)L=(-epsilon)/(di//dt)`