Alternating Current

An ac voltage $V=220 \sin \left(2 \times 10^3 t\right)$ Volt is applied to a series LCR circuit. Then the current amplitude in this circuit is:
(Given : $L=10 \mathrm{mH}, C=25 \mu \mathrm{~F}, R=100 \Omega$ )

The peak value of an alternating current is 5 A and frequency is 60 Hz . How long will the current, starting from zero, take to reach the peak value?

An ac circuit contains a resistance of $1 \mathrm{k} \Omega$, a capacitor of $0.1 \mu \mathrm{~F}$ and an inductor of 1 mH connected in series. The resonance frequency of the circuit is approximately:

To an ac power supply of 220 V at 50 Hz , a resistor of $20 \Omega$, a capacitor of reactance $25 \Omega$ and an inductor of reactance $45 \Omega$ are connected in series. The corresponding current in the circuit and the phase angle between...

In the circuit shown below, the inductance \(L\) is connected to an ac source. The current flowing in the circuit is \(I=I_0 \sin \omega t\). The voltage drop \(\left(V_L\right)\) across \(L\) is

The amplitude of the charge oscillating in a circuit decreases exponentially as \(Q=Q_0 e^{-R t/2 L}\), where \(Q_0\) is the charge at \(t=0 \mathrm{~s}\). The time at which charge amplitude decreases to \(0.50 Q_0\) is nearly:
[Given that ...

A step up transformer is connected to an ac mains supply of \(220 \mathrm{~V}\) to operate at \(11000 \mathrm{~V}, 88\) watt. The current in the secondary circuit, ignoring the power loss in the transformer, is

A \(10 \mu \mathrm{F}\) capacitor is connected to a \(210 \mathrm{~V}, 50 \mathrm{~Hz}\) source as shown in figure. The peak current in the circuit is nearly \((\pi=3.14)\) :

In an ideal transformer, the turns ratio is \(\frac{N_P}{N_S}=\frac{1}{2}\). The ratio \(V_S: V_P\) is equal to (the symbols carry their usual meaning) :

For very high frequencies, the effective impedance of the circuit (shown in the figure) will be:-

The maximum power is dissipated for an ac in a/an:

If Z\(_1\) and Z\(_2\) are the impedances of the given circuits (a) and (b) as shown in figures, then choose the correct option

An ac source is connected in the given circuit. The value of $\phi$ will be :

The net impedance of circuit (as shown in figure) will be :

The magnetic energy stored in an inductor of inductance \(4 ~\mu \mathrm{H}\) carrying a current of \(2 \mathrm{~A}\) is :

An ac source is connected to a capacitor C. Due to decrease in its operating frequency

A \(12 \mathrm{~V}, 60 \mathrm{~W}\) lamp is connected to the secondary of a step down transformer, whose primary is connected to ac mains of \(220 \mathrm{~V}\). Assuming the transformer to be ideal, what is the current in the primary wind...

In a series LCR circuit, the inductance \(L\) is \(10 ~\mathrm{mH}\), capacitance \(C\) is \(1 ~\mu \mathrm{F}\) and resistance \(R\) is \(100 ~\Omega\). The frequency at which resonance occurs is :-

A standard filament lamp consumes 100 W when connected to 200 V ac mains supply. The peak current through the bulb will be :

An inductor of inductance 2 mH is connected to a 220 V, 50 Hz ac source. Let the inductive reactance in the circuit is X1. If a 220 V dc source replace the ac source in the circuit, then the inductive reactance in the circuit is X2. X1 and ...

Given below are two statements
Statement I : In an a.c circuit, the current through a capacitor leads the voltage across it.
Statement II : In a.c circuit containing pure capacitance only, the phase difference between the current and voltag...

A series LCR circuit with inductance 10 H, capacitance 10 \(\mu\)F, resistance 50 \(\Omega\) is connected to an ac source of voltage, V = 200sin(100t) volt. If the resonant frequency of the LCR circuit is v0 and the frequency of the ac sour...

The peak voltage of the ac source is equal to

A series LCR circuit containing 5.0 H inductor, 80\(\mu\)F capacitor and 40\(\Omega\) resistor is connected to 230V variable frequency ac source. The angular frequencies of the source at which power transferred to the circuit is half the po...

A step down transformer connected to an ac mains supply of 220 V is made to operate at 11 V, 44W lamp. Ignoring power losses in the transformer, what is the current in the primary circuit ?

A capacitor of capacitance 'C', is connected across an ac source of voltage V, given by V = V0sin\(\omega\)tThe displacement current between the plates of the capacitor, would then be given by :

An inductor of inductance L, a capacitor of capacitance C and a resistor of resistance 'R' are connected in series to an ac source of potential difference 'V' volts as shown in figure. Potential difference across L, C and R is 40V, 10V and ...

A series LCR circuit is connected to an ac voltage source. When L is removed from the circuit, the phase difference between current and voltage is \({\pi \over 3}\). If instead C is
removed from the circuit, the phase difference is again $...

A 40 \(\mu\)F capacitor is connected to a 200 V. 50 Hz ac supply. The rms value of the current on the circuit is, nearly :

An inductor 20 mH, a capacitor 100 \(\mu\)F and
a resistor 50 \(\Omega\) are connected in series across
a source of emf, V = 10 sin 314 t. The power
loss in the circuit is

The magnetic potential energy stored in a
certain inductor is 25 mJ, when the current
in the inductor is 60 mA. This inductor is of
inductance

Figure shows a circuit that contains three identical resistors with resistance R = 9.0 \(\Omega\) each, two identical inductors with inductance \(L\) = 2.0 mH each, and an ideal battery with emf \(\varepsilon = 18V\). The current \(i\) th...

The potential differences across the resistance, capacitance and inductance are 80 V, 40 V and 100 V respectively in an L-C-R circuit. The power factor of this circuit is

Which of the following combinations should be selected for better tuning of an L-C-R circuit used for combination ?

A 100 \(\Omega\) resistance and a capacitor of 100 \(\Omega\) reactance are connected in series across a 220 V source. When the capacitor is 50% charged, the peak value of the displacement current is

An inductor 20 mH, a capacitor 50 \(\mu F\) and a resistor 40 \(\Omega\) are connected in series across a source of emf V = 10 sin 340t. The power loss in A.C. circuit is

A small signal voltage V(t) = V0 sin\(\omega\)t is applied across an ideal capacitor C

A resistance 'R' draws power 'P' when connected to an AC source. If an inductance is now placed in series with the resistance, such that the impedance of the circuit becomes 'Z'. the power drawn will be

A series R-C circuit is connected to an alternating voltage source. Consider two situations :
(a)  When capacitor is air filled.
(b)  When capacitor is mica filled.
Current through resistor is \(I\) and voltage across capacitor is \(V\) ...

A transformer having efficiency of 90% is working on 200 V and 3 kW power supply. If the current in the secondary coil is 6 A, the voltage across the secondary coil and the current in the primary coil respectively are

The primary of a transformer when connected to a dc battery of 10 Volt draws a current of 1 mA. The number of turns of the primary and secondary windings are 50 and 100 respectively. The voltage in the secondary and the current drawn by the...

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

The current \((I)\) in the inductance is varying with time according to the plot shown in figure.

Which one of the following is the correct variation of voltage with time in the coil ?

In an electrical circuit R, L, C and a.c. voltage source are all connected in series. When L is removed from the circuit, the phase difference between the voltage and the current in the circuit is If instead, C is removed from the circuit, ...

The instantaneous values of alternating current and voltage in a circuit are given as
\(i = {1 \over {\sqrt 2 }}\) sin (100 \(\pi\)t) ampere
\(e = {1 \over {\sqrt 2 }}\sin \left( {100\pi t + {\pi \over 3}} \right)\) Volt
The average powe...

In the ac circuit an alternating voltage e = \(200\sqrt 2\)sin100t volts is connected to a capacitor of capacity 1 \(\mu\)F. The r.m.s. value of the current in the circuit is

An ac voltage is applied to a resistance R and an inductor L in series. If R and the inductive reactance are both equal to 3 \(\Omega\), the phase difference between the applied voltage and the current in the circuit is

A coil has resistance 30 ohm and inductive reactance 20 ohm at 50 Hz frequency. If an ac source, of 200 volt, 100 Hz, is connected across the coil, the current in the coil will be

The r.m.s. value of potential difference V shown in the figure is

A 220 volt input is supplied to a transformer. The output circuit draws a current of 2.0 ampere at 440 volts. If the efficiency of the transformer is 80%, the current drwn by the primary windings of the transformer is