Basic Electricity, Voltage, Amps, Relationships Among Voltage, Current, and Resistance, Wattage

Basic Electricity

Electricity is energy that has properties that can be measured in various ways.

Voltage

If you measure the electrical charge on one side of a light bulb and compare it to the electrical charge on the other side of a bulb, you see a difference in charge. The potential difference in charge creates an electrical force that drives the electrons through the system between two points, and is called voltage, which is measured in units called volts. Voltage is measured when the power is on.

Amps

The volume of electrons (or electricity) flowing through an electrical system is called current. If you measure the number of electrons, or electrical current, at any point in this system, you find the same value as at any other point because the current is constant throughout the system. (This assumes that there is only a single wire in the entire closed electrical system.)

Electrical current is measured in amperes, abbreviated amps. An ammeter is a measuring device that measures electrical current in amps. You place the ammeter in the path of the electrical flow so that the electrons must flow through the ammeter. The measurement is taken with the power on and might not be completely accurate because the ammeter can influence the circuit.

The Relationship Between Voltage and Current

As the electrical potential difference (or voltage) increases, the electrical current increases; as the voltage decreases, the current decreases. There is a direct relationship between voltage and current.

Ohms

Resistance in an electrical system is a property that opposes the flow of electricity. As the electrical resistance increases, the electricity decreases. As the resistance decreases, the electricity increases. When there is more resistance to the flow of electricity, the flow of electrons decreases. In addition, when too much electricity flows through a wire, heat energy is created in the wire (similar to friction). This heat energy can cause the wire to melt or burn, which can result in an electrical fire, just as too much water current in a pipe can cause it to burst. Reducing the size of a wire reduces the amount of electricity that can safely flow through. Electrical resistance is measured in ohms.

Resistors are devices used in electrical circuits to resist the flow of electricity. Resistors control the flow of electricity in a circuit.

Relationships Among Voltage, Current, and Resistance

Voltage and current have a direct relationship. This means that when voltage increases, current increases. Resistance has an inverse relationship between voltage and current. This means that as resistance increases, either current or voltage decreases. As resistance decreases, either current or voltage increases. This last statement is known as Ohm’s Law. A similar statement defines the relationship among the units of measure—volts, amps, and ohms. One volt drives a current of one amp through a resistance of one ohm.

Wattage

Our discussion of electricity would not be complete without covering one last measure of electricity. Wattage is the total amount of power needed to operate an electrical device. Electrical power increases as both voltage and current increase. Wattage, measured in watts, is calculated by multiplying volts by amps in a system.