/ˈkʌrənt/
noun … “Flow of electric charge.”
Current is the rate at which electric charge flows through a conductor or circuit, typically carried by electrons in metals or ions in electrolytes. It is one of the fundamental concepts in electricity, working alongside voltage and resistance to describe how electrical energy moves and performs work in circuits.
Key characteristics of Current include:
- Unit: measured in amperes (A), representing one coulomb of charge per second.
- Direction: conventional current flows from positive to negative, opposite to electron flow.
- Types: Alternating current (AC) reverses direction periodically; Direct current (DC) flows in one direction.
- Relationship to voltage and resistance: governed by Ohm’s law, I = V / R.
- Effects: produces magnetic fields, generates heat, and enables work to be done in electrical devices.
Applications of Current include powering electronic devices, motors, lighting, heating elements, and communication systems.
Workflow example: Calculating current through a resistor:
voltage = 9 -- Volts
resistor = 1000 -- Ohms
current = voltage / resistor
print(current) -- 0.009 A (9 mA)
Here, current is determined by the applied voltage and resistance, flowing through the circuit to perform work.
Conceptually, Current is like the flow of water through a pipe: the amount of water passing a point per unit time corresponds to electric current.
See Voltage, Resistance, Power, AC, DC.