An $LCR$ series circuit with $100 \,\Omega$ resistance is connected to an $AC$ source of $200 \,V$ and angular frequency $300 \,rad/s$. When only the capacitance is removed,the current leads the voltage by $60^o$. When only the inductance is removed,the current lags the voltage by $60^o$. Then the current and power dissipated in the $LCR$ circuit are respectively:

$A$ resistor $R=300 \Omega$ and a capacitor $C=25 \mu F$ are connected in series with a $50 \ V, \frac{50}{\pi} \ Hz$ $AC$ source. The average power dissipated in the circuit is (in $W$)

Consider the infinite ladder circuit shown below. For which angular frequency $\omega$ will the circuit behave like a pure inductance?

Answer the following questions:
$(a)$ In any $ac$ circuit, is the applied instantaneous voltage equal to the algebraic sum of the instantaneous voltages across the series elements of the circuit? Is the same true for $rms$ voltage?
$(b)$ Why is a capacitor used in the primary circuit of an induction coil?
$(c)$ An applied voltage signal consists of a superposition of a $dc$ voltage and an $ac$ voltage of high frequency. The circuit consists of an inductor and a capacitor in series. Show that the $dc$ signal will appear across $C$ and the $ac$ signal across $L$.
$(d)$ $A$ choke coil in series with a lamp is connected to a $dc$ line. The lamp is seen to shine brightly. Insertion of an iron core in the choke causes no change in the lamp's brightness. Predict the corresponding observations if the connection is to an $ac$ line.
$(e)$ Why is a choke coil needed in the use of fluorescent tubes with $ac$ mains? Why can we not use an ordinary resistor instead of the choke coil?

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 $f$?

$A$ direct current of $10 \,A$ is superimposed on an alternating current $I = 40 \cos \omega t \; (A)$ flowing through a wire. The effective value of the resulting current will be ....... $A$.