An $e.m.f.$ of $12 \, V$ is produced in a coil when the current in it changes at the rate of $45 \, A/min$. The inductance of the coil is ....... $H$.

When the current through an inductor is changed from $2 \,A$ to $6 \,A$ in time $2 \,s$, the emf induced in it is $3 \,V$. Then the inductance of the inductor is (in $\,H$)

The self-inductance $L$ of a solenoid of length $l$ and area of cross-section $A$ increases . . . . . . (Here with a fixed number of turns $N$).

The dimensions of self or mutual inductance are given as

An emf of $2.8 \ mV$ is induced in a rectangular loop of area $150 \ cm^2$ when the current in the loop changes from $3 \ A$ to $8 \ A$ in a time of $0.2 \ s$. Then the self-inductance of the loop is (in $\mu H$)

Two coils $A$ and $B$ have $180$ and $360$ turns respectively. $A$ current of $1 \text{ A}$ flows through both the coils. Due to a current of $1 \text{ A}$ in coil $A$, a flux per turn of $0.8 \times 10^{-3} \text{ Wb}$ is linked with coil $A$. Due to a current of $1 \text{ A}$ in coil $B$, a flux per turn of $1 \times 10^{-3} \text{ Wb}$ is linked with coil $B$. The self-inductance of coil $A$ is $L_A$ and the self-inductance of coil $B$ is $L_B$. The ratio $L_A$ to $L_B$ is: