List of top Physics Questions on Alternating current asked in UP Board XII

L, C and R are connected in series with an alternating current source. When there will be resonance in the circuit? What will be the nature of impedance during resonance?
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State the Faraday's laws of electromagnetic induction. Define self induction, state the Lenz's law regarding direction of self induced current. In a coil, due to change of current at the rate of 1 A/s an e.m.f. of 1 V is produced. What will be the coefficient of self inductance of the coil?

Give formula for power loss in an alternating circuit. Find the e.m.f. of source in the circuit and the phase difference between resultant potential and the current flowing in the circuit. (Series R-L-C driven by an AC source with \(V_R=40\) V across the resistor, \(V_L=50\) V across the inductor and \(V_C=20\) V across the capacitor.)
In L–C–R circuit power factor will be 1, if:

Find out from the given circuit shown above: (i) Impedance (ii) power factor (iii) phase difference between current and voltage. The series circuit has \(L = 10\ \text{H}\), \(R = 500\ \Omega\) and \(C = 20\ \mu F\), driven by an AC source \(V = [200\sin 100t]\ \text{Volt}\).
In an L-C-R circuit, the inductive reactance of a coil is 400 Ω and the capacitive reactance of a condenser is 100 Ω and \( R = 400\ \Omega \). Find the power factor of the circuit.
In an AC circuit, if the current \(i = 2\sin\omega t\) ampere and the voltage \(V = 5\cos\omega t\) volt, then the power loss will be:
Explain the meaning of power factor and wattless current in alternating current circuits.

An alternating current source is connected in the following figure (a series combination of an inductor \(L\), a capacitor \(C\) and a resistor \(R\) across an AC source of rms voltage \(V\)). Determine the value of current flowing in the resistance \(R\) in the condition of resonance.
In the resonance condition, the current drawn from the source by a parallel resonant (L-C) circuit is:
State the working principle of a transformer and mention the energy losses occurring in it.

The variation between V and I with time (t) in two alternative circuits is shown in the above graphs. Which one of the curves of circuit is capacitive and which one is resistive?
The unit of \( \sqrt{LC} \) (where \( L \) is inductance and \( C \) is capacitance) is:

Find the readings of the voltmeter and ammeter in the given AC circuit. Is the circuit in the state of resonance?
Given: \( V = 135\sqrt{2}\,\sin 100t \) volt, \( R = 45\,\Omega \), \( X_L = 4\,\Omega \), \( X_C = 4\,\Omega \). The voltmeter is connected across the series L-C combination and the ammeter is in series with the circuit.