INTRODUCING OHM’S LAW Original Power Point Created by Paul Lane Modified by Georgia Agricultural Education Curriculum Office June 2002

WHERE DID OHM’S LAW COME FROM? Georg Simon Ohm BORN: March 16, 1789, Erlangen, Bavaria [Germany] DIED: July 6, 1854, Munich German physicist who discovered the law that states that the current flow through a conductor is directly proportional to the potential difference (voltage) and inversely proportional to the resistance. Ohm became professor of mathematics at the Jesuits' College at Cologne in While his work greatly influenced the theory and applications of current electricity, it was so coldly received that Ohm resigned his post at Cologne. He accepted a position at the Polytechnic School of Nürnberg in Finally his work began to be recognized; in 1841 he was awarded the Copley Medal of the Royal Society of London and was made a foreign member a year later. The physical unit measuring electrical resistance was given his name: OHMS LAW.

To understand Ohm’s Law we must first learn some simple electrical symbols: SINGLE CELL FUSE SINGLE ACTION SWITCH CAPACITOR BULB RESISTOR

ELECTRICAL SYMBOLS ONE WAY DIODE VARIABLE RESISTOR EARTH WIRES CROSSING WIRES JOINING IGNITION COIL CONTACT POINT

WHAT IS OHM’S LAW? V= I x R Where:V=Voltage I=Current R=Resistance EXAMPLE: A 12 volt battery supplies power to a heated rear window which has a resistance of 18 ohm’s. Calculate how much current is following through the heated window.

V = 12 VOLTS R = 18 OHM’S V IR Using this simple triangle we can see that: I = V R I = I = 0.6 ANSWER: About 6 amps of current followed through the heated window.