If a current of $10 \, A$ flows in one second through a coil,and the induced $e.m.f.$ is $10 \, V$,then the self-inductance of the coil is:

An air-cored solenoid with length $30 \ cm$,area of cross-section $25 \ cm^2$ and number of turns $500$ carries a current of $2.5 \ A$. The current is suddenly switched off for a brief time of $10^{-3} \ s$. How much is the (nearly) average back e.m.f. induced across the ends of the open switch in the circuit (in $V$)? (Ignore the variation of magnetic field near the ends of solenoid)

What is the self-inductance of a coil which produces a self-induced $EMF$ of $5 \ V$ when the current changes from $3 \ A$ to $2 \ A$ in $1 \ ms$?

$A$ graph of magnetic flux $(\phi)$ versus current $(I)$ is plotted for four inductors $A, B, C, D$. Which inductor has the largest value of self-inductance?

The dimensions of self or mutual inductance are given as

The self-inductance of an air-core inductor (solenoid) is $0.03 \ mH$. By introducing an iron core into the inductor, the self-inductance increases to $30 \ mH$. The relative permeability of the core used is: