. Both AC (Alternating Current) and DC(Direct Current) describe types of current flow in a circuit.
. DC: Charge flows only in one direction.
. AC: Changes direction of flow periodically.
How is electric current produced?
. By moving a metal wire through magnetic field.
. Electric generator rotates a coil of wire through magnetic field.
. The produced current is AC.
. Slip rings transfer power across rotating structure.
. Carbon brush conducts current between stationary wires and rotatory wires.
. It produces sinusoidal, triangular or square wave. Mostly sine wave is prefered for easy calculations.
. Can easily convert into different voltages using transformer.
. To produce DC current there are many methods:
- Chemical reactions in Batteries
- Using Rectifiers to convert AC current into DC current
- Using ring commutators in the circuit to automatically change rotation of current produced.
Usage of AC and DC:
. AC current is mostly preferred to supply electricity over longer distances.
. AC is easily stepped up and down with the help of transformers.
. While sending to longer distances, voltage is stepped up and sent.Power loss will be minimum.
. If DC is used instead, transformers won't work.
. DC-DC voltage converters can be used but they are very complex.
. So, it is not suitable for longer distance transmissions because power is lost.
. DC is used in most of electronic appliances which run on IC's and other elements which require constant voltage.
. In this case, AC is not suitable because voltage goes on varying.
Differences between AC and DC:
Property | AC | DC |
---|---|---|
Transferring Energy | Safer to transfer over longer distances and provide more power. | Cannot travel over longer distances. Loses power. |
Direction | Energy constantly changes direction | Flows in one direction |
Current | Magnitude varies with time | Magnitude is constant |
Cause of current flow | Rotating magnets along wire | Steady magnetism |
Obtained from: | AC Generators, mains | Batteries, cells |
Frequency | 50Hz or 60Hz | 0 |
Types | Sine, triangular, square | Pure and Pulsating |
Power Factor | Lies between 0-1 | Always 1 |
Usage | Home, Office supply | Most of electronic devices |
Conversion | Use Rectifiers to convert AC to DC | Use Inverters to convert DC to AC |
Safety | AC is safer since voltage comes to equilibrium at times | Voltage is constant, not much safer. |