Luigi Galvani (1737-1798)

“Animal electricity”

Galvanic Cells

Alessandro Volta showed that chemical reactions

between metal electrodes and an

electrolytic fluid can induce electrical current.

Voltaic Piles and Batteries

Reactions in some batteries can be

reversed to recharge the battery.

Dry cell batteries – “safe” and “portable”

Batteries and Electrical Current

• Electrical current– Flow of charged particles– Symbol: I – Units: Coulombs/second (C/s)

• Voltage– the difference in electrical charge between two

points in a circuit (electrical “pressure”)– Symbol: V– Units: volts (V)

• Battery– Converts chemical energy to kinetic energy

(energy of flowing charges)

Electric Circuits

• Electric circuit– Unbroken path of material carrying electricity– Electrical conductor

• Circuit components1. Source2. Closed path3. Device to use electrical energy

• Ohm’s Law– Current is directly proportional to voltage V and inversely

proportional to resistance R – In symbols: I = V / R

• Electric Power: P = I × V

Two Kinds of Electric Circuits