Electric Potential

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)

Potential Energy Potential Energy: The energy of position.

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

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.

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

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.

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

9 volt Battery Most batteries 1.5 volts

Car battery 12 volts

USA Outlet 120 volts

European outlets 240 volts

http://www.maxtravelz.com/travel-guides/Electrical_systems.html

World Voltage Map http://www.maxtravelz.com/travel-guides/Electrical_systems.html

50,000 – 100,000 volts!

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.

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.

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.

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.

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)

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)

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

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________________