Alternating Current

If wattless current flows in an AC circuit, then the circuit is:
A. LR circuit
B. Purely capacitive circuit
C. Purely resistive circuit
D. LCR circuit

A solenoid having resistance $R=60 \Omega$ and inductance $L=0.4 \mathrm{H}$ is connected to an AC source $V=100 \sqrt{2} \sin 200 t$.
Find the maximum current.

An AC generator having 400 turns and an area of cross section of $2 \times 10^{-3} \mathrm{~m}^2$ rotates with an angular speed of $200 \pi \mathrm{rad} \mathrm{s}^{-1}$ in a uniform magnetic field of strength 0.4 T . The generator is conne...

In a given circuit, the instantaneous values of the alternating voltage and current are $V=0.5 \sin \left(80 \pi t+\frac{\pi}{3}\right)$ volt and $I=0.5 \sin (80 \pi t)$ ampere respectively. Find the average power consumed in that circuit.

A source of alternating emf $\varepsilon=\varepsilon_0 \sin (\omega t)$ is connected to a capacitor. Then the instantaneous current in the circuit is: ˋ

An electronic device operates at 2 MHz . The oscillating circuit has an inductance $20 \times 10^{-5} \mathrm{H}$. What is the capacitive reactance of the resonant circuit?

If $R$ and $L$ denote resistance and inductance of a material, then the dimension of $L R$ will be:

A bulb of resistance 280 Ohm is supplied with a voltage $\mathrm{V}=400 \sin \pi \mathrm{t}$. The peak current is

An ideal inductor is connected across a capacitor. Oscillations of energy $K$ are set up in the circuit. The capacitor plates are slowly drawn apart such that the frequency of oscillations is quadrupled. The work done in the process is

An LCR series ac circuit is at resonance with 10 V each across $\mathrm{L}, \mathrm{C}$ and R . If the resistance is halved, the respective voltage across $R, C$ and $L$ are

The instantaneous values of alternating current and voltages in a circuit are $\mathrm{I}=\frac{3}{\sqrt{2}} \sin (200 \pi t)$ ampere and $\mathrm{V}=\frac{3}{\sqrt{2}} \sin \left(200 \pi t+\frac{\pi}{6}\right)$ volt. What is the average po...

A series LCR circuit having $\mathrm{R}=44 \Omega, \mathrm{~L}=2 \mathrm{H}$ and $\mathrm{C}=25 \mu \mathrm{~F}$ is connected to a variable frequency of 220 V . What is the average power transferred to the circuit in one complete cycle if t...

In a pure inductive circuit, a sinusoidal voltage $V(t)=200 \sin 250 t$ is applied to a pure inductance of $\mathrm{L}=0.02 \mathrm{H}$. The current through the coil is:

A power transmission line feeds input power at 2200 V to a step-down transformer with its primary windings having 2000 turns. The output power is delivered at 220 V by the transformer. If the current in the primary of the transformer is 2 A...

The ratio of the number of turns of the primary coil to the secondary coil of an ideal transformer is $5: 1$. The primary is connected to 220 V supply. What is the output power of the transformer if the output resistance is $11 \Omega$ ?

In which of the following circuit do we find the current and voltage in phase?

What should be the value of the inductance of the coil which is to be connected to 220 V , 50 Hz supply so that maximum current of $3 \sqrt{2} A$ flows through the circuit ?

A coil of inductance \(1 \mathrm{H}\) and resistance \(100 \Omega\) is connected to an alternating current source of frequency \(\frac{50}{\pi} \mathrm{~Hz}\). What will be the phase difference between the current and voltage?

The capacitance of a parallel plate capacitor is \(400 \mathrm{~pF}\). It is connected to an ac source of \(100 \mathrm{~V}\) having an angular frequency \(100 \mathrm{~rad~s}^{-1}\). If the rms value of the current is \(4 \mu \mathrm{A}\),...

A transformer which steps down \(330 \mathrm{~V}\) to \(33 \mathrm{~V}\) is to operate a device having impedance \(110 \Omega\). The current drawn by the primary coil of the transformer is :

A coil offers a resistance of \(20 \mathrm{~ohm}\) for a direct current. If we send an alternating current through the same coil, the resistance offered by the coil to the alternating current will be :

In the \(\mathrm{A} . \mathrm{C}\). circuit given below, voltmeters \(\mathrm{V}_1\) and \(\mathrm{V}_2\) read \(100 \mathrm{~V}\) each. Find the reading of the voltmeter \(\mathrm{V}_3\) and the ammeter \(\mathrm{A}\).

When an A.C. source is connected to a inductive circuit,

An AC voltage source of variable angular frequency \(\omega\) and fixed amplitude \(\mathrm{V}_0\) is connected in series with a capacitance \(\mathrm{C}\) and an electric bulb of resistance \(\mathrm{R}\) (inductance zero). When \(\omega\)...

A transformer has 400 turns in its primary winding and 800 turns in its secondary winding. The primary voltage is \(20 \mathrm{~V}\) and the load in the secondary is 4 ohm. The current in the primary, assuming it to be an ideal transformer,...

A group of devices having a total power rating of 500 watt is supplied by an \(\mathrm{AC}\) voltage \(E=200 \sin \left(3.14 t+\frac{\pi}{4}\right)\). Then the r.m.s. value of the circuit current is

What should be the inductance of an inductor connected to \(200 \mathrm{~V}, 50 \mathrm{~Hz}\) source so that the maximum current of \(\sqrt{2}\) A flows through it?

\(220 \mathrm{~V}\) ac is more dangerous than \(220 \mathrm{~V}\) dc Why?

In an electrical circuit \(R, L, C\) and \(\mathrm{AC}\) 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 \(\pi / 3\). If instead ...

In the case of an inductor

In the series L-C-R circuit shown, the impedance is

The instantaneous values of alternating current and voltages in a circuit given as
$$\begin{aligned} & i=\frac{1}{\sqrt{2}} \sin (100 \pi t) \mathrm{amp} \\ & e=\frac{1}{\sqrt{2}} \sin (100 \pi t+\pi / 3) \text { volt } \end{aligned}$$
The ...

The AC voltage across a resistance can be measured using a

An alternating voltage = 200 \(\sin 100t\) is applied to a series combination of \(R=30\Omega\) and an inductor of 400 mH. The power factor of the circuit is,

A series L-C-R circuit is connected to an AC source of 220 V and 50 Hz shown in figure. If the readings of the three voltmeters \(V_1,V_2\) and \(V_3\) are 65 V, 415 V and 204 V respectively, the value of inductance and capacitance will be

A DC ammeter and a hot wire ammeter are connected to a circuit in series. When a direct current is passed through circuit, the DC ammeter shows 6 A. When AC current flows through circuit, what is the average readings in DC ammeter and the A...

During the phenomenon of resonance

If impedance is \(\sqrt3\) times of resistance, then find phase difference.

What should be the value of self-inductance of an inductor that should be connected to 220 V 50 Hz supply, so that a maximum current of 0.9 A flows through it?

For the same resonant frequency, if L is changed from L to \({L \over 3}\), then capacitance should change from C to

The formula of capacitative reactance is

For a series L-C-R circuit at resonance, which statement is not true?