Basics of Electricity Magic of Electrons © 2011 Project Lead The Way, Inc.

What is Electricity? Involves the movement of electrons Is invisible PLTW Gateway® Unit 4 – Lesson 4.1 – What is Electricity? What is Electricity? Involves the movement of electrons Is invisible Provides light, heat, sound, motion . . . Has been practical for use over the last 100 years

History 2500 years ago, the Greeks rubbed amber with other materials. Electricity PLTW Gateway® Unit 4 – Lesson 4.1 – What is Electricity? History 2500 years ago, the Greeks rubbed amber with other materials. They discovered that this process would attract feathers and other lightweight materials to the amber.

. . .opposite charges attract and like charges repel. Electricity PLTW Gateway® Unit 4 – Lesson 4.1 – What is Electricity? History . . .opposite charges attract and like charges repel. Ben Franklin suggested that . . . + -

. . .opposite charges attract and like charges repel. Electricity PLTW Gateway® Unit 4 – Lesson 4.1 – What is Electricity? History . . .opposite charges attract and like charges repel. Ben Franklin suggested that . . . The Law of Charges explains why the electrons continue to be bonded to the nucleus. The law of charges was first discovered by Charles Augustin de Coulomb. It explains that all magnetic objects have the tendency to repel or attract to one another. Like charges repel one another and unlike charges attract one another. The attraction or repulsion occurs in a straight line, there is a force between the charges and the bigger the charges the greater the force. + +

Electricity PLTW Gateway® Unit 4 – Lesson 4.1 – What is Electricity? Electron Flow An electron from one atom can knock out an electron from another atom.

Electricity PLTW Gateway® Unit 4 – Lesson 4.1 – What is Electricity? Electron Flow Electricity is created as electrons collide and transfer from atom to atom. Play Animation

What Makes Up Electricity? PLTW Gateway® Unit 4 – Lesson 4.1 – What is Electricity? What Makes Up Electricity? Let’s compare it to something we know --- Water!

Water Analogy Tank = Battery Pipe = Wiring Faucet = Switch Tank Faucet Presentation Name PLTW Gateway® Unit # – Lesson #.# – Lesson Name Water Analogy Tank Faucet Pipe It might be necessary to remind students what an analogy is. Tank = Battery Pipe = Wiring Faucet = Switch

Current Current: The flow of electric charge Tank (Battery) Presentation Name PLTW Gateway® Unit # – Lesson #.# – Lesson Name Current Current: The flow of electric charge Tank (Battery) Faucet (Switch) Pipe (Wiring) It might be necessary to remind students what an analogy is. When the faucet (switch) is off, is there any flow (current)? NO When the faucet (switch) is on, is there any flow (current)? YES

Current in a Circuit When the switch is off, there is no current. Presentation Name PLTW Gateway® Unit # – Lesson #.# – Lesson Name Current in a Circuit off on off on When the switch is off, there is no current. When the switch is on, there is current.

Voltage Voltage: The force (pressure) behind the flow of current Presentation Name PLTW Gateway® Unit # – Lesson #.# – Lesson Name Voltage Voltage: The force (pressure) behind the flow of current Tank (Battery) Faucet (Switch) Pipe (Wiring) When the faucet (switch) is off, is there any pressure (voltage)? YES – Pressure (voltage) is pushing against the pipe, tank, and the faucet. When the faucet (switch) is on, is there any pressure (voltage)? YES – Pressure (voltage) pushes flow (current) through the system.

Presentation Name PLTW Gateway® Unit # – Lesson #.# – Lesson Name Voltage in a Circuit off on off on The battery provides voltage that will push current through the bulb when the switch is on.

Resistance Resistance: The opposition to the flow of current. Presentation Name PLTW Gateway® Unit # – Lesson #.# – Lesson Name Resistance Resistance: The opposition to the flow of current. Tank (Battery) Faucet (Switch) Pipe (Wiring) All materials have resistance. Conductors have little resistance. Insulators provide a lot of resistance. Some electronic components (resistors) have a specific resistance. These are often needed to reduce current in order to protect other components or to adjust the amount of current that goes to other components. What happens to the flow (current) if a rock gets lodged in the pipe? Flow (current) decreases.

Resistance in a Circuit Presentation Name PLTW Gateway® Unit # – Lesson #.# – Lesson Name Resistance in a Circuit Resistor off on Resistors are components that limit the flow of electricity. Reducing current causes the bulb to become more dim.

(You might already know these!) Types of Electricity (You might already know these!)

Types of Electricity Static Electricity Current Electricity The electrical charge an object develops as a result of having an unequal number of protons and electrons. (Static Electricity) When the imbalance of charge becomes too great, the electrons will move. (Current Electricity) The movement happens when a push (voltage) is applied to the electrons. Current Electricity The movement of electrons through a conductor.

Static Electricity Uncontrollable Electricity Lightening Static Cling Wool socks on a carpet “shocks”

Alternating Current (AC) Current Electricity Two Types: Direct Current (DC) Alternating Current (AC)

Direct Current The electrons flow in the same direction all the time, from negative to positive. - +

Direct Current Comes from Batteries Converted from Alternating Current Used for electronic devices including Computers iPods Cell phones Anything that has a “charger” Batteries provide current electricity through a chemical reaction. In today’s activity students will “build” a DC battery. Anything that has a cord with a “box” attached to the cord is converting AC current to DC current. Show examples of cords with converter boxes. Demonstrate using the multimeter to measure the voltage of the battery. Show how switching the leads from the multimeter on the battery changes the + or - sign in the display. This happens because DC voltage is directional. Black lead to negative and red lead to positive will show a positive voltage. Black lead to positive and red lead to negative will give a negative voltage. (This will help students answer the Conclusion question #2 in the next activity.)

The electrical current (movement of electrons) changes direction. Electricity PLTW Gateway Unit 6 – Lesson 6.1 – What is Electricity? Alternating Current The electrical current (movement of electrons) changes direction.

Alternating Current Comes from Generators Electricity PLTW Gateway Unit 6 – Lesson 6.1 – What is Electricity? Alternating Current Comes from Generators Coal burning and nuclear power plants Hydroelectric power plants Wind and solar generators Used for Motors Heaters Lights Anything that plugs into the wall

Electricity PLTW Gateway® Unit 4 – Lesson 4.1 – What is Electricity? Image Resources Microsoft, Inc. (2008). Clip Art. Retrieved September 10, 2008, from http://office.microsoft.com/en-us/clipart/default.aspx