If the input voltage $V_i$ to the circuit below is given by $V_i(t) = A \cos (2 \pi f t)$ and the output voltage is given by $V_o(t) = B \cos (2 \pi f t + \phi)$,which one of the following four graphs best depicts the variation of $\phi$ versus $f$?

At a particular angular frequency,the reactance of a capacitor and that of an inductor are the same. If the angular frequency is doubled,the ratio of the reactance of the capacitor to that of the inductor will be:

In an $AC$ circuit, the instantaneous current is zero when the instantaneous voltage is maximum. In this case, the source may be connected to:
$A$. Pure inductor.
$B$. Pure capacitor.
$C$. Pure resistor.
$D$. Combination of an inductor and capacitor.
Choose the correct answer from the options given below:

An $AC$ source of $20\,V$ (assuming standard frequency $f = 50\,Hz$ for calculation) is connected to an inductance of $100\,mH$,a capacitance of $100\,\mu F$,and a resistance of $120\,\Omega$ as shown in the figure. The time in which the resistance,having a thermal capacity of $2\,J/^{\circ}C$,will get heated by $16^{\circ}C$ is ..........$s$.

An inductor stores $16 \ J$ of magnetic field energy and dissipates $32 \ W$ of thermal energy due to its resistance when an $A.C.$ current of $2 \ A$ $(rms)$ and frequency $50 \ Hz$ flows through it. The ratio of inductive reactance to its resistance is . . . . . . . $(\pi=3.14)$

The effective current $I$ in the given circuit at very high frequencies will be $.......A$