Electric Currents Summary

Electric Current

Electric current is the flow of electric charge, specifically electrons, through a conductor like a wire.

Generating Current

Voltage is required to make charges flow. Alessandro Volta invented the voltaic cell, which uses chemical reactions to create an electric potential difference between two electrodes, forming a battery when multiple cells are combined. Current needs a ground, a common conductor, to ensure a path to a large charge reservoir.

Measuring Current

Current is measured in amperes (A), where one ampere is one coulomb of charge per second. The conventional direction of current is the direction positive charge would flow, opposite to the actual flow of electrons.

Voltage, Current, and Resistance

High voltage typically corresponds to high current. Resistance, measured in ohms, impedes the flow of electrons. One ohm allows one ampere of current to flow with one volt of potential.

Ohm's Law

Ohm's law states that voltage (V) is equal to current (I) times resistance (R) when resistance is constant: V = IR. Some materials are Ohmic materials which means that Ohm's law works quite well with them.

Superconductors

Superconductors are materials that, when extremely cold, exhibit zero resistance, allowing for highly efficient electricity transmission.

Power

Power is the rate at which energy is transformed, measured in watts. The power (P) used by a device is equal to the current (I) times the voltage (V): P = IV.

Power and Resistance

The power consumed by a resistor can also be expressed as P = I^2R or P = arc{V^2}{R}, derived from Ohm's law.