AC and DC Current

Most recent answer: 10/22/2007

Q:
What is AC and DC current?
- Iqra (age 13)
Pakistan
A:
Iqra -

Great question! AC and DC stand for ’alternating current’ and ’direct current,’ respectively. Current means the flow of electrical charge from place to place. DC keeps flowing one way. If It flows a long time, that means that current flows around in a loop, always the same way. A battery provides a steady push, so battery circuits (like in flashlights) have DC.

Alternating current (AC) is what you get from most wall outlets. It flows back and forth, switching directions. Most motors are designed to run off ac. Many electronic devices need dc somewhere inside, so they have devices called rectifiers that convert ac to dc.

-Tamara and Mike

(published on 10/22/2007)

Follow-Up #1: Motor speeds

Q:
I need steady rotation for a sfaft,Do i have to use acor dc motor and why?
- DMAK (age 22)
Egypt
A:
Most AC motors run at constant speed.  The speed of a DC motor will depend on the applied voltage, an advantage if you want to control it.  Take a look at the wickipedia article for some more information: http://en.wikipedia.org/wiki/Electric_motor

LeeH

(published on 10/22/2007)