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Ohm’s Law. Voltage. V. I. R. Resistance. Current. George Ohm. 1827 - published the Ohm’s Law formula The formula was based on his experiments with electrical resistance. Ohm’s Law shows the relationship between voltage, current, and resistance. Ohm’s Law Formula. R = V I
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Ohm’s Law Voltage V I R Resistance Current
George Ohm • 1827 - published the Ohm’s Law formula • The formula was based on his experiments with electrical resistance. • Ohm’s Law shows the relationship between voltage, current, and resistance.
Ohm’s Law Formula R=V I • R is for resistance • V is for voltage • I is for current • Resistance is measured in ohms. • Voltage is measured in volts. • Current is measured in amps.
Other Formulas • The equation can be rearranged to solve for current and voltage. I =V R and V= IR • So, if any two values are known, you can solve for the third.
With Constant Resistance • The greater the voltage, the greater the current. • So, if we double the voltage, what happens to the current? Voltage = Current
With Constant Voltage • For a greater resistance, the current is decreased. • So, if resistance is doubled, what happens to the current? Resistance = Current
Example Solving for Resistance An automobile headlight is connected to a 12-volt battery. If the resulting current is 0.40 amps, what is the resistance of the headlight? Answer: 30 Ω
Example Solving for Voltage In order for a waffle iron to operate efficiently, a current of 12 A must flow through its coils. If the resistance is 10 Ω , what must the voltage be? Answer: 120 V
Example Solving for Current You light a light bulb with a 1.5 volt battery. If the bulb has a resistance of 10 Ω , how much current is flowing? Answer: 0.15 A
References • Prentice Hall Physical Science Textbook pgs. 658 – 659 ISBN: 0-13-062649-X • http://www.ndt-ed.org/EducationResources/HighSchool/Electricity/ohmslaw.htm