voltagecurrent

Voltage and current are two fundamental electrical quantities that describe how electrical energy is stored and used in a circuit. Voltage, or electric potential difference, drives the flow of charges. Current is the rate at which charges pass a point, measured in amperes. The two are linked by the properties of the circuit's elements.

In an ideal resistor, Ohm's law states V = IR, so the current through the element is proportional to the applied voltage, with resistance R as the constant of proportionality. When a voltage is applied, the resulting current depends on the load.

Power in a circuit is given by P = VI, the rate at which energy is transferred. For a resistor, this can be expressed as P = I^2R or P = V^2/R.

Voltage sources provide a potential difference, while the circuit elements determine how much current flows. Measurement is performed with a voltmeter across a component and an ammeter in series to read current.

In alternating current systems, voltage and current vary with time. Impedance extends Ohm's law to AC circuits, combining resistance and reactance; V and I may be out of phase, described by phasors.

Understanding voltage and current is essential in designing safe and efficient electrical systems, from simple electronics to power distribution.