Understanding power factor is very easy if you are clear with the nature of inductor and capacitor. Power factor is observed in either inductive or capacitive circuits only.
Definition: it is the magnitude of difference in the phase of voltage and current wave form.
Power in a network is given as P=VIcosΔ
Here the term cos∆ is called the power factor.
Power factor in inductive circuit: if an inductor is present in the circuit , then on initial application of power supply it will tend to oppose the rise of current. hence the current lags behind the voltage.
Power factor in capacitive circuits: if a capacitor is present in the circuit, then on initial application of power supply it will tend to oppose the rise in voltage. Hence the voltage lags behind current.
Power factor for resistive networks is 0 , because the don’t oppose change in current or voltage.
Comments and Reations
Amish Devgan : Thanks for such a simple answer however I have a question. Why does power factor is seen only in Inductor and capacitor? Why not in resistor?
Respose by Bhumiraj Gohil
Glad you asked. Let’s get into bit more detailed analysis of inductive, capacitive and resistive circuits to get more feel about power factor.
Inductive network
The main property of an inductor is to generate self induced emf across itself and opposite to source voltage (lenz’s law) . In doing so it has to obstruct the rise in current when the power supply is switched on. Thus we see current lagging in inductive networks.
Capacitive network
The main property of a capacitor is to generate static potential difference across its plates. Thus the voltage applied across the plate will be used by capacitor to accumulate opposite charges. The capacitor will build a potential difference opposing the power supply voltage. So voltage lags in such network.
Resistive networks
Resistance is basically a phenomena of providing a opposition to the flow of free electrons . Also according to Ohm’s law V=IR , the graph of voltage versus current is linear. Hence the increment/decrement factor of voltage to current remains constant . Thus no phase difference is observed.
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