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Alternating current
Beginner
Current that reverses direction periodically.
i = I₀ sinωtAC current and voltage vary sinusoidally in time, reversing direction f times per second: i = I₀ sin ωt. Mains: 50 or 60 Hz. AC is easily transformed, so it's used for power distribution.
230 V RMS mains has a peak of 325 V.
AC is not 'weaker' than DC for the same RMS.
In more detail
Alternating current reverses direction periodically, usually as a sinusoid. It can be transmitted efficiently over long distances by using transformers to change voltage.
Real-world uses
- Mains supplies in homes deliver alternating current at 50 or 60 hertz.
- Power grids transmit AC at high voltage to reduce losses.
- The mains supply in homes alternates 50 or 60 times a second, which is why lamps flicker very slightly if you look closely.
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Frequently asked questions
Why is AC used for mains power?
It can be stepped up and down easily with transformers, which makes long-distance transmission efficient.
Is AC dangerous?
It can be, and it is often more hazardous than DC at the same voltage for some effects on the body.
Why is AC used for the grid?
It can be stepped up or down easily with transformers, which makes long-distance transmission efficient.