# Electric currents

A slide is

• a low-friction path,
• for a child,
• to move from a place of higher GravE=$mgh$,
• to a place of lower GravE

A conductor is...

• a low-resistance path,
• for some charge (usually electrons),
• to move from a place of higher ElectricE=$qV$,
• to a place of lower ElectricE.

Electric energy = charge $\cdot$ voltage

Charge measured in Coulombs, voltage measured in Volts

### Current

Current is moving charge.

Measured in Amps: 1 Amp = 1 Coulomb / sec

Electric current will take the path of lowest resistance to get from high voltage to low voltage.

Usually that means *anything but air*. Voltages have to get *very high* before air will become a conductor.

### AC / DC

If the voltage difference between two places is constant (like a battery) $\Rightarrow$ constant current (direct current).

If the voltage difference between two places is changing (like a wall socket) $\Rightarrow$ varying current (alternating current).