How to Use Ohm's Law for Voltage, Current and Resistance
May 07, 2008 by
Ohm's Law is a mathematical equation governing the relationship between voltage, current, and resistance within a DC electrical circuit. In this article I will review the definitions of these three properties of an electrical circuit, the relationship between them described by Ohm's Law,
and offer some practical considerations to keep in mind when using Ohm's Law to calculate unknown quantities in an electrical circuit.
Voltage
Voltage is the electromagnetic force that causes the electrons to flow within an electrical circuit. The greater the voltage, the more current will flow, assuming a constant resistance to the flow of electrons within a circuit. Voltage may be thought of as the force or pressure that sets the electrons in motion within a circuit. The basic unit of electromotive force is the "Volt".
Current
Electrical current is the measure of the quantity of electrons flowing through a conductor or through a circuit. As the Voltage (i.e. pressure or force) increases, more electrons will flow and the circuit's electrical current will increase. Likewise, if one raises or lowers the resistance to the flow of electrons within a circuit, the electrical current will decrease or increase, respectively. The basic unit of electrical current is the "Ampere" or just "Amp" for short.
Resistance
Electrical resistance is the opposition to the flow of electrical current within an electrical current. All conductors present some resistance to the flow of electrons, however minimal. Most practical circuits have a "load" which converts the electrical current to some other form of energy, and this load will likewise present an opposition to the flow of electrons as it performs its work via the electrical current. The basic unit of electrical resistance is the "Ohm".
Ohm's Law
Ohm's Law is the equation that defines the relationship between voltage, current, and resistance in a direct current electrical circuit. Here is Ohm's Law, written algebraically:
E = I * R
(where E stands for Voltage in Volts, I stands for Current in Amperes, and R stands for Resistance in Ohms)
How to use Ohm's Law
Voltage
Voltage is the electromagnetic force that causes the electrons to flow within an electrical circuit. The greater the voltage, the more current will flow, assuming a constant resistance to the flow of electrons within a circuit. Voltage may be thought of as the force or pressure that sets the electrons in motion within a circuit. The basic unit of electromotive force is the "Volt".
Current
Electrical current is the measure of the quantity of electrons flowing through a conductor or through a circuit. As the Voltage (i.e. pressure or force) increases, more electrons will flow and the circuit's electrical current will increase. Likewise, if one raises or lowers the resistance to the flow of electrons within a circuit, the electrical current will decrease or increase, respectively. The basic unit of electrical current is the "Ampere" or just "Amp" for short.
Resistance
Electrical resistance is the opposition to the flow of electrical current within an electrical current. All conductors present some resistance to the flow of electrons, however minimal. Most practical circuits have a "load" which converts the electrical current to some other form of energy, and this load will likewise present an opposition to the flow of electrons as it performs its work via the electrical current. The basic unit of electrical resistance is the "Ohm".
Ohm's Law
Ohm's Law is the equation that defines the relationship between voltage, current, and resistance in a direct current electrical circuit. Here is Ohm's Law, written algebraically:
E = I * R
(where E stands for Voltage in Volts, I stands for Current in Amperes, and R stands for Resistance in Ohms)
How to use Ohm's Law
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