Alternating current:
There are two types of current one is called alternating current, or "AC". AC current is an exact type of electric current in which the direction of the current's run is inverted, or alternated, on a regular basis.
This is the electricity that we use in our house and that you use to power most of your electrical devices. Alternating current is not easy to explain like direct current. The electricity is not afford as a single, constant voltage, but rather as a sine wave (sinusoidal) that over time starts at zero, increases to a maximum value, and then decreases to a minimum value, and it goes on again and again.
But in simple direct current circuits are usually described only by their voltage, alternating current circuits need more detail. First of all, if the voltage goes from a positive value to a negative value and reverse again, what do we say is the voltage? Is it zero, because it averages out to zero? That would look like to mean that there is no power there at all.
But visualize if you will, a wave of water flowing across the surface of the sea. The peaks and troughs of the wave seem to "cancel each other out", but the wave clearly exists and has power. Alternating current is also like this.
Direct Current:
The second and simpler type of current is called direct current, abbreviated "DC". Direct current is no different electrically from alternating current excluding for the fact that it flows in the same direction at all times.
This is the type of current that is produced by batteries, static, and lightning. A voltage is produced, and possibly stored, until a circuit is completed. When we use a mobile, flashlight, portable radio, transportable CD player or almost any other type of portable or battery-powered device, you are using direct current. Most DC circuits are relatively low in voltage.
In DC circuits, the current is always the same polarity, which means that in a two-wire circuit, one "wire", or side of the circuit, is always negative, and the negative side is always the one that sends the current. There is no pulsating because there is no periodic change in current flow.
DC current is more effective for long-distance, high-voltage conduction because it results in less energy lost in conduction, but the cost of converting DC current to AC is somewhat high, so DC is usually cost-effective only for long-distance conduction.
There are two types of current one is called alternating current, or "AC". AC current is an exact type of electric current in which the direction of the current's run is inverted, or alternated, on a regular basis.
This is the electricity that we use in our house and that you use to power most of your electrical devices. Alternating current is not easy to explain like direct current. The electricity is not afford as a single, constant voltage, but rather as a sine wave (sinusoidal) that over time starts at zero, increases to a maximum value, and then decreases to a minimum value, and it goes on again and again.
But in simple direct current circuits are usually described only by their voltage, alternating current circuits need more detail. First of all, if the voltage goes from a positive value to a negative value and reverse again, what do we say is the voltage? Is it zero, because it averages out to zero? That would look like to mean that there is no power there at all.
But visualize if you will, a wave of water flowing across the surface of the sea. The peaks and troughs of the wave seem to "cancel each other out", but the wave clearly exists and has power. Alternating current is also like this.
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| Waves of DC and AC current |
Direct Current:
The second and simpler type of current is called direct current, abbreviated "DC". Direct current is no different electrically from alternating current excluding for the fact that it flows in the same direction at all times.
This is the type of current that is produced by batteries, static, and lightning. A voltage is produced, and possibly stored, until a circuit is completed. When we use a mobile, flashlight, portable radio, transportable CD player or almost any other type of portable or battery-powered device, you are using direct current. Most DC circuits are relatively low in voltage.
In DC circuits, the current is always the same polarity, which means that in a two-wire circuit, one "wire", or side of the circuit, is always negative, and the negative side is always the one that sends the current. There is no pulsating because there is no periodic change in current flow.
DC current is more effective for long-distance, high-voltage conduction because it results in less energy lost in conduction, but the cost of converting DC current to AC is somewhat high, so DC is usually cost-effective only for long-distance conduction.
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