List of top Physics Questions on Alternating Current

For an ac source rated at 220 V, 50 Hz, which of the following statements is correct?
In A.C. circuits, what is the difference between impedance and resistance? Write the formula for power factor in L-C-R circuit.
In an alternating circuit, the reading of the voltmeter is 220 V. Write the peak value of the voltage.
Describe a series L, C, R resonant circuit.
Three ac circuits are shown in the figures with equal currents. Explain with reason, if the frequency of the voltage \( E \) is increased then what will be the effect on the currents in them.
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What is meant by wattless current?
The voltage and current of an ac circuit are represented as \( V = 100 \sin(100t) \) volt and \( i = 100 \sin(100t + \frac{\pi}{3}) \) mA respectively. The power dissipated in the circuit is:
In the given figure, LCR circuit is shown. Voltage of the alternating current source is \( V = 100 \sin (500 t) \) volt. Calculate for the circuit:
What is meant by resonant circuit? Write down the required condition for the L-C-R series resonant circuit and expression for the frequency in resonant condition.
What is meant by the wattless current?
The peak value of an alternating current is 14.14 Amp., and its frequency is 50 Hz. Draw current-time graph for two cycles. Find r.m.s. value of current. What time will the current take to reach the peak value starting from zero ?
The peak voltage in a 220 volt A.C. source is
What is meant by Wattless current? A capacitor of 15 \(\mu\)F is connected to an AC source of 220 V and 50 Hz. Find out reactance of circuit and rms value of AC current.
Voltage (V) equation in an alternating current circuit is represented by \( V = 40 \sin(100 \pi t) \) volt. Here t is in second. Draw the time-voltage graph for one cycle with proper scale.
A lamp “50 watt and 100 volt” is to be connected to AC mains of 200 volt 50 Hz. Calculate the capacity of condenser required in series of lamp.
The resistance of 8 ohm and inductive reactance of 6 ohm are connected in series in an alternating current circuit. The impedance of circuit will be :
An ac source of voltage \( v = v_m \sin \omega t \) is connected to a series combination of LCR circuit. Draw the phasor diagram. Using it, obtain an expression for the impedance of the circuit and the phase difference between applied voltage and the current.
A voltage \( v = v_0 \sin \omega t \) applied to a circuit drives a current \( i = i_0 \sin (\omega t + \phi) \) in the circuit. The average power consumed in the circuit over a cycle is:
Differentiate between the peak value and root mean square value of an alternating current. Derive the expression for the root mean square value of alternating current, in terms of its peak value.

The alternating current \( I \) in an inductor is observed to vary with time \( t \) as shown in the graph for a cycle.
 

alternating current I in an inductor

Which one of the following graphs is the correct representation of wave form of voltage \( V \) with time \( t \)?}

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 the current and the voltage is, respectively :
Figure shows the variation of inductive reactance \( X_L \) of two ideal inductors of inductance \( L_1 \) and \( L_2 \) with angular frequency \( \omega \). The value of \( \frac{L_1}{L_2} \) is: 
variation of inductive reactance
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 (\(V_L\)) across \(L\) is:
Question Figure
A resistor and an ideal inductor are connected in series to a \( 100 \sqrt{2} \, \text{V}, 50 \, \text{Hz} \) AC source. When a voltmeter is connected across the resistor or the inductor, it shows the same reading. The reading of the voltmeter is:
The r.m.s. value of a current given by \( i = (i_1 \cos \omega t + i_2 \sin \omega t) \) is: