1. Electric Potential

2. Today’s Tasks Be able to define Voltage
Understand how electricity flows through a circuit
Experiment to build a working circuit
Learn how to correctly draw a simple circuit (schematic)

3. Potential Energy
Potential Energy: The energy of position.

4. Electric Potential Energy
With no electric field, a charge will not move… +

5. Electric Potential Difference
Voltage: The electric potential difference between two points. B A
Because of the electric field, charge would be pushed from A to B.

6. Voltage: Electric Potential Difference
S.I. Unit volt (V) = joule / coulomb
To use the water analogy, we can think of voltage as the potential energy of each unit of charge, which would be the height of the water tower. The higher the elevation, the more the potential energy. B A

7. Water Analogy
The Water analogy can be useful to explain the different properties of electricity and circuits. The voltage can be described as the height of the water tower, which would be the potential energy, or in other words the capacity of the water to do work. The current would be the flow rate of the water, and in a circuit that is measured in coulombs of charge per second as opposed to the water’s gallon per second rate. The resistance can be equated to the water’s ability to flow. A large hose would allow a lot of water to flow per second, and offer low resistance. A smaller hose would impede the flow of water and cause less water to flow per second, representing a higher resistance.

8. Summary on Voltage
The electric potential difference (or voltage) is the “pressure” that sets the flow of charge in an electric circuit.

9. 9 volt
Battery
Most batteries
1.5 volts

10. Car battery
12 volts

11. USA Outlet
120 volts

12. European outlets
240 volts

14. World Voltage Map

15. 50,000 – 100,000 volts!

16. Voltage questions
1. Moving an electron within an electric field would change the ____ the electron.
mass of
amount of charge on
potential energy of
To use the water analogy, we can think of voltage as the potential energy of each unit of charge, which would be the height of the water tower. The higher the elevation, the more the potential energy.

17. Voltage questions 2. Voltage is defined as _________.
the amount of charge
the amount of force on a charge
electric potential difference
To use the water analogy, we can think of voltage as the potential energy of each unit of charge, which would be the height of the water tower. The higher the elevation, the more the potential energy.

18. Voltage questions
3. The SI unit for voltage is the volt. If I have a 9 volt battery, what would that mean in terms of other units?
9 newtons per coulomb
9 joules per coulomb
9 coulombs per joule
To use the water analogy, we can think of voltage as the potential energy of each unit of charge, which would be the height of the water tower. The higher the elevation, the more the potential energy.

19. Voltage questions
4. If an electrical circuit were analogous to a water slide, then the battery voltage would be comparable to
the speed of the water
the distance that water flows
c. the water pressure
d. the amount of water flowing
To use the water analogy, we can think of voltage as the potential energy of each unit of charge, which would be the height of the water tower. The higher the elevation, the more the potential energy.

20. Voltage and Circuits
Circuit: A loop of connected conductors (wires) that allows an energy supply to push electric charge from high to low energy.
Load
Switch
Voltage Supply (battery)

21. Circuit Schematic
Light bulb: coverts electric energy into light and heat energy
Switch: Open switch = OFF
Closed circuit = ON
Current: Amount of charge that flows through a circuit.
Resistance: a component in a circuit that resists the flow of current (e.g. light bulb). It also converts electric energy into another form of energy.
Power Supply: provides electric potential difference (voltage)

22. Water analogy quiz Electric Circuit Water Pipes Wires Pipes Charge
Current
Water flow
Voltage
Pressure
Voltage supply
Pump
Switch
Valve
Resistance
Pinched/narrow Pipe

23. Exit quiz Draw the following circuit schematics….
A voltage supply, 2 lightbulbs in series.
A battery, a light bulb, a switch.
Water analogy…
What is current like ________________
What is voltage like________________
What are the pipes like________________