The current in an $L$-$R$ circuit builds upto $\frac{3}{4}\mathrm{th}$ of its steady state value in $4 \mathrm{s}$. The time constant of this circuit is

Some magnetic flux is changed from a coil of resistance $10 \mathrm{\Omega }$. As a result an induced current is developed in it, which varies with time as shown in figure. The magnitude of change in flux through the coil in $\mathrm{Wb}$ is

The current $i$ in an induction coil varies with time $t$ according to the graph shown

in figure. Which of the following graphs shows the induced $emf\left(E\right)$ in the coil with time?

Switch $S$ of the circuit shown in figure is closed at $t=0$. If $e$ denotes the induced $\mathrm{emf}$ in $L$ and $i$, the current flowing through the circuit at time $t$, which of the following graphs is correct?

A capacitor of capacity $2 \mu \mathrm{F}$ is charged to a potential difference of $12 \mathrm{V}$. It is then connected across an inductor of inductance $0.6 \mathrm{mH}$. The current in the circuit at a time, when the potential difference across the capacitor is $6 \mathrm{V}$

In the circuit shown, the coil has inductance and resistance. When $X$ is joined to $Y$, the time constant is $\tau$ during growth of current. When the steady state is reached, heat is produced in the coil at a rate $P$. $X$ is now joined to $Z$,