4 - Amperes, Volts, and Ohms

We use different units to measure different things. There are special units to measure electricity, too. Three of the most important are AMPERE, VOLT, AND OHM.
AMPERE - The size of an electric current depends on how many electrons pass a point in a circuit every second. The greater the number of electrons the larger the current. Fewer electrons mean smaller current. The size of an electric current is measured in amperes, or "amps". We can say that ampere is another name for electric current.
VOLT - Nothing moves by itself. A force is needed to make something move. Electricity needs a force to move it. Electrons move in a circuit because force pushes them. The name for the force or pressure that pushes electrons is electromotive force, or EMF. The strength of the EMF, or force, is measured in Volts.
OHM - Ohms measure the resistance of the flow of electrons. You know that a wire resists the flow of electrons. The amount of resistance is measured in Ohms.
There is a connection between amps, volts, and ohms. When one changes, there must be a change in one or both of the others. The rule for figuring these changes is called Ohm's Law.

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