$A$ solenoid is connected to a battery so that a steady current flows through it. If an iron core is inserted into the solenoid,the current will

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

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 ....... $H$.

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:

The $SI$ unit of self-inductance is:

$A$ circuit having a self-inductance of $1 \text{ H}$ carries a current of $1 \text{ A}$. To prevent sparking when the circuit is broken,a capacitor which can withstand $500 \text{ V}$ is connected across the switch. What is the minimum value of the capacitance of the capacitor (in $\mu \text{ F}$)?