AC Vs DC (Alternating Current Vs Direct Current) - Diffen

Origins of AC and DC current

A magnetic field near a wire causes electrons to flow in a single direction along the wire, because they are repelled by the negative side of a magnet and attracted toward the positive side. This is how DC power from a battery was born, primarily attributed to Thomas Edison's work.

Alternating and Direct current. The horizontal axis is time and the vertical axis represents voltage.

AC generators gradually replaced Edison's DC battery system because AC is safer to transfer over the longer city distances and can provide more power. Instead of applying the magnetism along the wire steadily, scientist Nikola Tesla used a rotating magnet. When the magnet was oriented in one direction, the electrons flowed towards the positive, but when the magnet's orientation was flipped, the electrons turned as well.

Video Comparing Alternating and Direct Current

Use of transformers with Alternating Current

Another difference between AC and DC involves the amount of energy it can carry. For Direct Current (DC), each battery is designed to produce only one voltage level, and that voltage of DC cannot travel very far until it begins to lose energy.

But Alternating Current (AC) voltage can be bumped up or down in strength by another mechanism called a transformer. For example, AC current leaves the power plant and is transmitted at very high voltage across power lines; however, transformers located on electrical poles on the street change it into a lower voltage appropriate for home appliances like lamps and refrigerators.

Storage and Conversion From AC to DC and Vice Versa

AC can even be changed to DC by an adapter that you might use to power the battery on your laptop. DC can be "bumped" up or down, it is just a little more difficult. Inverters change DC to AC. For example, for your car an inverter would change the 12 volt DC to 120 Volt AC to run a small device. While DC can be stored in batteries, you cannot store AC.

References

• Wikipedia: Mains electricity by country
• Wikipedia: Alternating current
• Wikipedia: Direct current