- Voltage is the electromotive force that causes electrons to flow in a certain direction within a circuit. The unit of measure of this force is volts. When a source of electromotive force is connected to a circuit, electrons flow in a specific direction, depending on the other components within the circuit. If the source is unplugged, electrons will cease to flow. Examples of electromotive force sources include batteries and generators.
- The term amperage refers to the magnitude, or strength, of the current as it travels through the circuit. Physicists often refer to this measurement simply as current. Amperage is measured in amperes, or amps for short. Scientists use a device called an ammeter to measure the amperage in a circuit.
- Voltage and current are important factors in how much energy a circuit generates. If the voltage and current of a circuit are known, you can determine the power output, measured in watts, using the equation P = IV, where P is power, I is current and V is voltage. In order to use this equation, two of the values must be known. For example, if you have a lightbulb connected in a circuit to a six-volt battery and the bulb's power output is 100 watts, you can calculate the current of the system by rearranging the equation and using I = P/V.
- Resistors are sometimes used in circuits to reduce the flow of electrons through the circuit. These components are important to circuits because if too much current flows through it generates heat, which could melt the circuit. Resistance must be factored into the equation when it is present, because affects the current and voltage. The equation from Ohm's Law is used in this case, which is V = IR, where V again is voltage, I is current and R is resistance. You can use this equation in conjunction with P = IV to learn more about a specific circuit.
Voltage
Amperage
Equations
Resistors
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