925 B
925 B
| categories | tags | |||
|---|---|---|---|---|
|
|
Current
Electrical current is the movement of electrons from negatively charged atoms to negatively charged atoms when an appropriate external force is applied.
So current is the flow of electrons. Charge is the quantity that flows. Current exists because of the first law of electrostatics.
The amount of current is the sum of the charges of the moving electrons past a given point.
We use the symbol I to stand for current in equations.
Coulombs and amps
We measure charge in Coulombs (C). A Coulomb is an aggregate of the charge of several electrons because their individual charge is so small: 6.24 \cdot 10 ^{18} electrons.
We measure current in amps. When one coulomb of charge moves past a point in one second it is called an ampere (amp) represented as A.