Modeling and Measuring
Electricity
Section 2.2 p, 304
Learning Outcome
• Describe, using models, the nature of electrical
current; and explain the relationship among current,
resistance and voltage (e.g., use a hydro-flow model
to explain current, resistance and voltage)
• Apply Ohm’s law to calculate resistance, voltage and
current in simple circuits
Modeling Voltage and Amprage
• Remember
• Voltage is a measure of how much electrical energy each charged
particle carries
• The higher the voltage the is the greater the potential energy of each particle
(potential difference)
• Amperage
• Is the rate at which the electrical current is flowing (how many electrons)
Modeling Current
• Look at the following pictures, if these waterfalls represent the flow
of electricity, describe which ones have more voltage, or amps?
Resistance, Voltage, Amperage in Current
• Using the water model we can see the relationship between current,
voltage, and current
• Voltage, current, and resistance all affect the overall flow of electricity
Ohm’s Law
• Georg Simon Ohm was able to prove a mathematical link between
• Voltage (V)
• Current (amps) (I)
• Resistance (ohm’s (Ω)
• Ohm’s law states that as long as temperature stays the same
• The resistance of a conductor stays constant
• The current is directly proportional to the voltage applied
• Directly proportionate means that if one goes up the other will go up, if one goes down
the other will go down
Ohm’s Law isn’t perfect
• Ohm’s Law states that as long as temperature stays the same
• As conductors heat up and cool down the resistance they provide will change
• Cool temperatures resistance will be less
• Hotter temperatures resistance will increase (making it harder for current to flow)