AC vs. DC: What's the Difference?
Read the comparison below, or explore it visually. Create a visual lesson comparing ac and dc using available credits or plan allowance.
Alternating current (AC) repeatedly reverses its direction of flow, while direct current (DC) flows steadily in one direction. Household mains is AC, about 230 volts at 50 hertz in India and the UK and 120 volts at 60 hertz in the US, because transformers can easily step AC voltage up or down. Batteries, solar cells and the circuits inside phones and laptops use DC.
At a glance
| AC | DC | |
|---|---|---|
| Direction of flow | Reverses direction periodically | Flows in one direction only |
| Typical source | Power-station generators (alternators) | Batteries, solar cells, phone chargers |
| Frequency | 50 Hz (India, UK) or 60 Hz (US) | Zero: the current never reverses |
| Changing voltage | Easily stepped up or down by transformers | Needs electronic converter circuits |
| Common uses | Household mains, fans, large motors | Phones, laptops, LEDs, electric-vehicle batteries |
Which should you use?
AC is the right choice for carrying power from a power station to homes, because transformers raise it to hundreds of kilovolts for transmission and lower it to 230 V for the wall socket.
DC is used wherever energy is stored or electronics compute: a phone charger converts 230 V AC from the socket into about 5 V DC to charge the lithium-ion battery.