AC voltage, or Alternating Current voltage, is an electric potential difference that periodically reverses direction. It is commonly used in household and industrial power systems.
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AC voltage changes its polarity periodically over time, typically in a sinusoidal waveform.
The standard frequency of AC voltage in the United States is 60 Hz, while in many other countries it is 50 Hz.
Root Mean Square (RMS) value is often used to express AC voltage because it provides a measure of the equivalent DC voltage that would produce the same power dissipation.
Transformers are devices that can step up or step down AC voltages efficiently, which makes long-distance transmission of electrical power feasible.
Ohm's Law applies to AC circuits as well: $V_{rms} = I_{rms} \cdot R$, where $V_{rms}$ and $I_{rms}$ are RMS values of voltage and current respectively.
Review Questions
What is the typical frequency of AC voltage in most European countries?
How does the RMS value of an AC voltage compare to its peak value?
Explain how transformers utilize AC voltage for efficient power transmission.
Related terms
Direct Current (DC): An electric current or voltage that flows in one direction only and does not change polarity over time.
A device used to increase or decrease the amplitude of an AC voltage through electromagnetic induction.
$RMS$ Value: $RMS$ stands for Root Mean Square; it is a statistical measure of the magnitude of a varying quantity and useful for comparing AC and DC voltages.