Voltage

Related wiki pages: Electronic Theory, Capacitors. Resistors. Inductors, transformers

What is Voltage?
In practical terms, voltage is the difference in electrical potential between two points in a circuit. The unit of measurement is the volt (V), which is a measure of the energy per unit charge.

Voltage is one of the properties of an electric field, and can be measured in terms of:


 * its relationship to a common point. This is usually with respect to ground (zero volts)


 * the relationship between two points. This is usually known as the voltage across a device or the voltage across a circuit.

In physical terms, Voltage is the work required to move an electric charge between two points:

1 Volt is the force required to send one Ampere of current through a resistane of one Ohm.

Some Formulae

 * $$ V = \sqrt{PR} $$


 * $$ V = I \times R $$


 * $$ P = V \times R $$

where V = potential difference (volts), I = current intensity (amps), R = resistance (ohms), P = power (watts).

Voltage across Resistors, Capacitors and Inductors
Voltage cross a resistor (Resistor R):


 * $$ V_R = IR_R \!\ $$

Voltage across a capacitor (Capacitor C):


 * $$ V_C = IX_C \!\ $$

Voltage across an inductor (Inductor L):


 * $$ V_L = IX_L \!\ $$

Where V=voltage, I=current, R=resistance, X=reactance.