Power factor
The ratio of real power to apparent power in an circuit. Phase displacement and waveform distortion can affect it. Real power includes power dissipated as losses as well as useful output, so power factor is different from . A lower power factor means more is needed for the same real power at the same RMS voltage.
Using Power factor in context
Updated
A distinction worth remembering
Power factor compares real power with apparent power. For sinusoidal conditions it is related to phase displacement; distorted waveforms need a broader explanation than a phase angle alone.
Questions to take further
- How can I revise Power factor beyond the definition?
- Explain what Power factor describes, compare it with a related term and use it in a topic question. State any assumptions and what evidence you would need before applying the idea to real work.
Sources
- OpenStax University Physics: Real and apparent power — The physical principle used in this comparison; technical installation requirements remain separate.
Where Power factor fits in the learning path
The Electrical Science section covers these units:
- Circuit Fundamentals
Curriculum mapping: C&G 2365 Units 202/302.
See this section in the full curriculum
This section is on the free path. Lesson availability depends on content review and your learning path.
Read, practise, return
1. Read it in context
- Three-Phase PowerElectrical Science
- Ohm's LawElectrical Science
2. Try recalling, then explore practice
Use the memory prompt below to connect the vocabulary.
- Electrical Science — quiz previewFree · Electrical Science
3. Return to the meaning
After reading or practising, explain the idea in your own words, then check what you remembered.
Recall a related term
Which term fits this definition? Say it to yourself, then reveal it. This is a memory prompt, with no score or saved result.
Electrical power is the rate at which electrical energy is transferred, measured in watts (W) or kilowatts (kW). A 1 kW load transfers energy twice as fast as a 500 W load. In a DC circuit, power equals voltage multiplied by current. For AC loads, real power also depends on power factor, so multiplying voltage and current alone does not always give watts.
Electrical power
Read the Electrical power entryCompare related terms
Open a meaning to compare its role with Power factor, or follow its full entry.
Electrical power
Electrical power is the rate at which electrical energy is transferred, measured in watts (W) or kilowatts (kW). A 1 kW load transfers energy twice as fast as a 500 W load. In a DC circuit, power equals voltage multiplied by current. For AC loads, real power also depends on power factor, so multiplying voltage and current alone does not always give watts.
Read the Electrical power entryAC — Alternating Current
Alternating current reverses direction repeatedly, unlike direct current. An AC voltage also changes polarity over its cycle. Frequency, measured in hertz (Hz), tells you how many complete cycles occur each second. In a three-phase system, the three AC waveforms are offset in time; three-phase does not mean three times the frequency.
Read the AC entryEfficiency
The share of input energy or power that becomes the intended useful output, usually written as a percentage. Losses such as heat mean a real transformer or motor delivers less useful power than it takes in. Efficiency compares input with output; it is different from power factor, which compares real and apparent power in an AC circuit.
Read the Efficiency entryA definition is a start. Using it in a real question is where it sticks.