Alternating Current Questions

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

An inductor and a resister in series are connected to an A.C. supply of variable frequency. As the frequency of the soure is increased, the phase angle between current and the potential difference acr...

A resitance ′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 &#8...

40. An inductor 20 mH, a capacitor 50 μF and a resistor 40 Ω are connected in series across a source of emf V = 10 sin 340 t. The power loss in A.C. circuit is :...

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

For an RLC circuit driven with voltage of amplitude vm and frequency w0 = 1LC the current exhibits resonance. The quality factor, Q is given by :...

In an a. c. circuit, the instantaneous e.m.f. and current are given by e = 100 sin 30 t i = 20 sin 30t-π4 In one cycle of a.c., the average power consumed by the circuit and the wattless current ...

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

In the given circuit the reading of voltmeter V1 and V2 are 300 volts each. The reading of the voltmeter V3 and ammeter A are respectively...

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

An alternating EMF of frequency is applied to a series LCR circuit. For this frequency of the applied EMF,...

A condenser of capacity C is charged to a potential difference of V1 The plates of the condenser are connected to an ideal inductor of inductance L. The current through the inductor when the potential...

The current (I) in the inductance is varying with timeaccording to the plot shown in figure. Which one of thefollowing is the correct variation of voltage with time in thecoil?...

An ac voltage is applied to resistance R and an inductor L in series. If R and the inductive reactance are both equal to 3Ω, the phase difference between the applied voltage and the current in th...

In an a.c. circuit the voltage applied is E = E0 sin ωt. The resulting current in the circuit is I = I0 sin . The power consumption in the circuit is given by...

The phase difference between the alternating current and emf is π/2. Which of the following cannot be the constituent of the circuit?

A circuit has a resistance of 12 Ω and an impedance of 15 Ω. The power factor of the circuit will be

Alternating current can not be measured by D.C. ammeter because

In an oscillating LC circuit the maximum charge on the capacitor is Q. The charge on the capacitor when the energy is stored equally between the electric and magnetic field is...

The core of any transformer is laminated so as to