How electric charge flows, what determines its size and how engineers measure it safely.
What is electric current?
Electric current is the rate at which electric charge crosses a chosen surface: I = dQ/dt.
It is measured in amperes.
Conventional current is defined as positive charge flow, even though electrons in metals move in the opposite direction.
What determines current?
A voltage can produce current, but the result depends on resistance, capacitance, inductance, semiconductor behavior and the frequency of change.
Current may be steady, alternating, pulsed or carried by ions, electrons, holes or other charge carriers.
Why does it matter?
Current transfers energy, changes magnetic fields, heats materials, drives motors and carries signals.
Too much current can damage components, start fires or create dangerous shock. Fuses, breakers, current limiting and grounding provide protection.
Measuring current
An ammeter is placed in series so the same current passes through it. A real meter has resistance and therefore changes the circuit slightly.
Understanding current connects circuit equations to physical charge motion and safe design.
Ai disclosure: written with the help of AI (ChatGPT). You are encouraged to point out errors and omissions.  
