⦿ Chapter : Alternating current (AC) ⦿ Topic : Alternating current circuit containing resistor only and phasor diagram ...
Pure Resistive AC Circuit ::
The circuit containing only a pure resistance of R ohms in the AC circuit is known as Pure Resistive AC Circuit. The presence of inductance and capacitance does not exist in a purely resistive circuit. The alternating current and voltage both move forward as well as backwards in both the direction of the circuit. Hence, the alternating current and voltage follows a shape of the Sine wave or known as the sinusoidal waveform.
In the purely resistive circuit, the power is dissipated by the resistors and the phase of the voltage and current remains same i.e., both the voltage and current reach their maximum value at the same time. The resistor is the passive device which neither produce nor consume electric power. It converts the electrical energy into heat.
In an AC circuit, the ratio of voltage to current depends upon the supply frequency, phase angle, and phase difference. In an AC resistive circuit, the value of resistance of the resistor will be same irrespective of the supply frequency.
Let the alternating voltage applied across the circuit be given by the equation
E = E0 sin wt
Then the instantaneous value of current flowing through the resistor shown in the figure below will be:
I = E/R
= E0 sin wt /R
⁂ I = I0 sinwt
Phase Angle and Waveform of Resistive Circuit
From equation (1) and (3), it is clear that there is no phase difference between the applied voltage and the current flowing through a purely resistive circuit, i.e. phase angle between voltage and current is zero.
The voltage and the current in the purely resistive circuit are in phase with each other having no phase difference with phase angle zero. The alternating quantity reaches their peak value at the interval of the same time period that is the rise and fall of the voltage and current occurs at the same time.