Alternating Current
Alternating Current: Overview
This topic covers concepts, such as, Alternating Current,Alternating Voltage,AC Circuit etc.
Important Questions on Alternating Current
A capacitor is connected to source. The capacitive reactance and the RMS current would be:

The instantaneous current and voltage of an AC circuit are given by and . The power dissipation in the circuit is

A resistor of and a capacitor of 15.0 are connected in series to a 220 V, 50 Hz a.c. source. Calculate
(i) The current in the circuit.
(ii) The rms voltage across the resistor and the capacitor.

A standard filament lamp consumes when connected to ac mains supply. Calculate the peak current through the bulb.

In the given AC circuit, find maximum current through the capacitor

The RMS value of the time varying current from to is


A modulating signal is added to the carrier signal
for amplitude modulation. The combined signal is passed through a non-linear square law device. The output is then passed through a band pass filter. The bandwidth of the output signal of band pass filter will be .

If, then the R.M.S. value of current from to seconds is

Given below are two statements:
Statement-I: In an ac circuit, the current through a capacitor leads the voltage across it.
Statement-II: In a.c. circuits containing pure capacitance only, the phase difference between the current and the voltage is
In the light of the above statements, choose the most appropriate answer from the options given below:

In an AC circuit, the current is given by the equation . Calculate the time taken to reach from zero to first maximum value.

Calculate the RMS value of the emf for a cycle, whose time variation is shown in figure.

The variation of the instantaneous current and the instantaneous emf in a circuit are shown in the figure. Which of the following statements is correct?

An alternating current is given by . The RMS current is given by


A resistance of is connected to a source of alternating current rated . Find the time taken by the current to change from its maximum value to the rms value

If Volt, then the time taken to reach the maximum point from zero.

A capacitor is connected to a ac supply. Determine the rms value of the current in the circuit.


How does the rms voltage of AC is related to the peak value of AC voltage?
