9.1 Electric current

Define electric current.

Electric current is the flow of charge carriers (usually electrons) through a conductor. It is measured in amperes (A). Current flows from higher potential to lower potential.

What is quantisation of charge?

The charge on charge carriers is quantised, meaning that each charge carrier has discrete amount of charge.

State the formula for charge.

Q = It
where Q = charge (C), I = current (A), t = time (s).

State the smallest unit of charge.

The charge on an electron is the smallest unit of charge, about 1.6×10^-19, C.

Derive the equation I = Anvq.

Current I is charge per unit time. Considering a conductor of cross-sectional area A, number density of charge carriers n, drift velocity of carriers v, and charge of each carrier q:
I = Anvq.