PhysicsChapter 7: Current Electricity
A.C.
Introduction
Alternating current (a.c.) is electric current that repeatedly changes direction with time. In many power systems, both current and voltage vary approximately sinusoidally.
Definition
Frequency
The number of complete a.c. cycles per second is the **frequency. Unit: hertz (Hz)**
Period
**T = 1f** where: `T` = time for one complete cycle; `f` = frequency.
Mains Electricity
Electricity supplied to homes is typically a.c., though exact voltage and frequency depend on the country's electrical standard.
Why A.c. Is Useful
A.c. can be transformed easily to higher or lower voltages using transformers. This is important for electrical power transmission and distribution.
Waveform
A simple sinusoidal a.c. waveform alternates above and below zero, representing repeated reversal.
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Review the key facts, formulas and checks before you move on.A.C.
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A.C.
- Reverses
f
- Cycles per second
T=1/f
- T=1f
MAINS
- A.c.