What is the self-inductance of a solenoid of length $31.4 \ cm$,area of cross-section $10^{-3} \ m^2$,and total number of turns $10^3$?

The self-inductance $(L)$ produced by a solenoid of length '$l$' having '$N$' number of turns and cross-sectional area '$A$' is given by the formula (where $\phi$ = magnetic flux,$\mu_0$ = permeability of vacuum).

The length of a wire required to make a solenoid of length $l$ and self-induction $L$ is

Consider a toroid with a rectangular cross-section,of inner radius $a$,outer radius $b$,and height $h$,carrying $n$ number of turns. Then the self-inductance of the toroidal coil when current $I$ is passing through the toroid is:

$A$ coil of $N = 100$ turns carries a current $I = 5 \, A$ and creates a magnetic flux $\phi = 10^{-5} \, Wb$ per turn. The value of its inductance $L$ will be ...... $mH$.

When current in a coil changes from $2 \ A$ to $5 \ A$ in a time of $0.3 \ s$,if the emf induced in the coil is $40 \ mV$,then the self inductance of the coil is