Alternating current (ac)
Definition
Alternating current (AC) is an electric current that periodically reverses direction. Unlike direct current (DC), AC voltage and current change their magnitudes continuously with time.
5 Must Know Facts For Your Next Test
- The frequency of AC in most countries is 50 Hz or 60 Hz, depending on the region.
- AC voltage can be represented mathematically as $V(t) = V_0 \sin(\omega t)$, where $V_0$ is the peak voltage and $\omega$ is the angular frequency.
- Root Mean Square (RMS) value of AC is used to represent its effective voltage or current: $V_{rms} = \frac{V_0}{\sqrt{2}}$.
- Transformers are devices used to increase or decrease the voltage of alternating current.
- AC power can be calculated using the formula $P = V_{rms} I_{rms} \cos(\phi)$, where $\phi$ is the phase difference between voltage and current.
Review Questions
- What is the mathematical representation of AC voltage?
- How do you calculate the RMS value of an alternating current's peak voltage?
- What role do transformers play in alternating-current circuits?
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Related terms
Frequency: The number of cycles per second in an alternating current, measured in Hertz (Hz).
Transformer: A device used to change the voltage level in an AC circuit by electromagnetic induction.
Root Mean Square (RMS): A statistical measure of the magnitude of a varying quantity, often used to determine the effective value of AC voltage or current.
