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Current:
Current is the measure of the flow
of electrons passing through a given point in
a circuit in a given amount of time. The unit is the amp(ere). Since it
would be impractical to state the actual number of electrons flowing through
the conductor, one amp is defined by 1 coulomb per second. One coulomb
equals 6,240,000,000,000,000,000 electrons. For now, just remember that
it indicates the amount of current flow through a circuit.
I know that the water flow analogy is getting old but it is still a very good way to explain basic electrical properties to beginners. The diagram below shows a water pump, a couple of sections of pipe (marked 'a' & 'c') and a valve (marked 'b'). If the pressure (voltage) in pipe section 'a' is constant, and the valve is only slightly open the current flow into pipe 'c' is going to be small. If we open the valve to its halfway point, the current flow will increase but will still be somewhat limited. When the valve is fully opened, the flow will be as high as possible. As you can see, the flow of current is inversely proportional to the 'resistance' offered by the valve.
small valve opening = high resistance = reduced current flow
large valve opening = lower resistance = increased current flow
To follow the analogy from the voltage page... The following diagram shows faucets with both high and low current flow. Below the faucets you'll see a section of wire with electrons flowing through it. The wire with more electron flow has more current flow. The wire with fewer electrons has less current flow.
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