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 equivalent quantity of mass in electricity is . . . . . . .

$A$ circular coil consists of $70$ closely wound turns and has a radius of $10 \,cm$. An externally produced magnetic field of magnitude $2 \times 10^{-3} \,T$ is applied perpendicular to the coil. The net flux through the coil is found to vanish when the current in the coil is $2.2 \,A$. The inductance of the coil is: (in $\,mH$)

$A$ coil of self-inductance $L$ is connected in series with a bulb and an a.c. source. Brightness of the bulb decreases when

The current in a coil changes from $3 \,A$ to $1 \,A$ in $0.1 \,s$ in a coil of self-inductance $8 \,mH$. The emf induced in the coil is

The inductance of a close-packed coil of $400$ turns is $8 \, mH$. $A$ current of $5 \, mA$ is passed through it. The magnetic flux through each turn of the coil is