Phase Difference between Applied Voltage and Current in an AC Source

When an AC (alternating current) source is connected to a resistor, there is a phase difference between the applied voltage and the current flowing through it. This phase difference is determined by the properties of the resistor and the frequency of the AC source.

Definition of Phase Difference
The phase difference between two waveforms is the measure of the displacement in time or phase between corresponding points on the two waveforms. In the case of an AC source and a resistor, the phase difference is the angular difference between the applied voltage and the current flowing through the resistor.

Causes of Phase Difference
The phase difference between the applied voltage and current in a resistor is primarily caused by the reactance of the resistor. Reactance is the opposition offered by a circuit element to the flow of alternating current due to its capacitance or inductance.

Explaining the Phase Difference
When an AC voltage is applied to a resistor, the current flowing through it depends on the resistance and reactance. The reactance can be either capacitive or inductive.

- In a purely resistive circuit, the voltage and current waveforms are in phase, meaning there is no phase difference. The voltage and current reach their peak values and zero crossings at the same time.

- In a capacitive circuit, the current leads the voltage waveform. This means that the current reaches its peak value and zero crossings before the voltage waveform. The phase difference is negative, indicating that the current waveform is shifted ahead of the voltage waveform.

- In an inductive circuit, the current lags the voltage waveform. This means that the current reaches its peak value and zero crossings after the voltage waveform. The phase difference is positive, indicating that the current waveform is shifted behind the voltage waveform.

Measuring the Phase Difference
To measure the phase difference between the applied voltage and the current flowing through a resistor, various techniques can be used. One common method is to use an oscilloscope. By connecting the voltage and current waveforms to the oscilloscope, the phase difference can be observed and measured.

Conclusion
In conclusion, when an AC source is connected to a resistor, the phase difference between the applied voltage and the current flowing through it depends on the resistive and reactive components of the circuit. The reactance, whether capacitive or inductive, causes the current waveform to either lead or lag the voltage waveform, resulting in a phase difference. Measuring the phase difference can be done using an oscilloscope or other suitable instruments.

Phase angle between voltage and current is 0