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A Direct Current
There are two main types of current in our world. One is direct current (DC) which is a constant stream of charges in one direction. The other is alternating current (AC) that is a stream of charges that reverses direction. Let's look at DC power which was refined by Thomas Edison in the 1800s.
Moving in One Direction
The current in DC circuits is moving in a constant direction. The amount of current can change, but it will always flow from one point to another. Before we move on, we need to explain that current direction is different from the direction the charges move. Charges move from areas where there are excess negative charges to areas of positive charge. Charges move from "-" to "+" because it's the electrons that flow. Current moves in the other direction. When you set up a circuit, current is considered to move from the "+" to the "-" side.
Battery Basics
The best real-life example of direct current is a battery. Batteries have positive (+) and negative (-) terminals. If you take a wire and connect the positive and negative terminals on a battery, the electrons will begin to flow. When electrons move, current begins to flow. You can prove that the current is flowing if you connect a small light to the circuit. The light will begin to glow as the electrons pass through the filaments.
DC power is used all over the world. You will probably use direct current power whenever you carry something around that uses electricity. Everything that uses batteries runs on DC power. Other countries use more portable power supplies because they might not have electric wiring in their houses.
That electric wiring in your house is AC power and it is completely different than DC. There are machines that can convert DC to AC power. Those machines might be used to take a DC battery in a boat and convert the power to AC so that a refrigerator can use it.
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