An electric current is just the flow of electric charges. The word current comes from the Latin word currere, which means to run or to flow. If you remember, electric charges can only flow through conductors and that some materials, like metal, have loose electrons that move around. When a conductor is put between two charged objects, then the loose electrons which have now made an imbalance are repelled or are pushed away by the negatively charged object but are attracted to the positively charged object. When this happens then there is a flow of charge called a current and the two charged objects become balance again. If you find this a bit confusing go back to p. 2 and reviewWhat is it?
The amount of current flowing through is measured in amperes, or amps. If you read that something uses so many amps, then that is telling you the amount of current flowing through the object. You could compare current to water in a hose. It is like the amount of water flowing through the hose. The amount of electrons moving through the wire or conductor.
Some people say that voltage is like pressure, electric pressure. There is more to it then just that, but to make this easy for you to understand we will use that idea here. Pressure builds up at one end of the wire because of all of negatively charged electrons. It's just like water pressure building up in the hose. The water pressure in the hose will tell how fast the water is pushed through the hose. Well, the pressure causes the electrons to move through the wire towards the positive charge. This pressure is called voltage, and is measured in volts.
Generally, resistance is friction in the wire. Friction can get something hot. Rub the palms of your hands together very quickly; you can feel your hands getting warm. This is because of the friction being created. Electrical resistance result in the wire getting warm, it can get so hot that it will actually glow. The amount of heat depends on the size of the wire (diameter or thickness). The thinner the wire, the more the resistance (friction). Thin wires are used for electric lightbulbs because they heat up fasrer. The friction is caused by the electrons trying to get through the wire. The Ohm is the unit of measurment to show resistance.
Direct and Alternating Currents:
DC and AC
Direct Current (DC) is the type of electricity that we get from batteries. All of the electric charges move in only one direction from the negative end of the battery to the positve end.
Alternating Current (AC) is the type of electricity that we get from plugs in the wall. The electric charges flow back and forth.