Presentation Transcript

1. Introduction to Electricity

   Text 10.1: Pages 394-399
2. Agenda Minds On: Inquiry – Black Out!!! Case Study – Wind farms in Ontario What is Electric Charge? Static Electricity Charges & Friction Laws of Attraction & Repulsion Consolidation Activity – Quick Lab
3. Learning Goal By the end of this class, we should be able to: explain the characteristics and behaviour of electric charge
4. Inquiry Task How long could you go without power? How long could you go without your cell phone? How long could you go with out your computer?
5. Inquiry Task Black Out! – August 14, 2003
6. Inquiry Task – Where Does Our Power Come From?
7. Action – Case Study Unit Big Question – How can we meet the growing electrical needs and challenges in Ontario? Read the following article: http://www.cbc.ca/news/canada/story/2012/09/10/wind-farm-injunction-ontario-couple.html What are the main issues? What questions arise from this article?
8. Consolidation Electricity Concept Map Create a concept map about electricity p.g. 391 Include the following: Questions Terms Categories Sketches http://library.thinkquest.org/10aug-oracle-62/636923189/page_694594863.html
9. Where might you encounter…
10. Action - What is Electric Charge? Electric charges are charged particles that exert an electric force on each other These charged particles are very small There are millions of them on each hair standing on end These differences can also cause more “shocking” displays
11. That Sounds Familiar! An element is a pure substance that cannot be broken down into simpler substances. Elements are made up of even tinier particles called atoms Specifically neutrons, electrons and protons When the number of protons and electrons are the same the atom is neutral
12. How Can you “Charge” Something? Objects can then become charged when electrons move from one object to another Charge can then build up on the surface of an object when there is an excess of electrons This is called static charge or static electricity
13. Static Electricity It is called “static” because the charge generally stays in a fixed position until given an “escape route”
14. What is this Object? Positive, Negative or Neutral? Tree: Cloud: Ground:
15. What Causes Electrons to Move? All solid materials are charged by the transfer of electrons But what causes an electron to move? When objects rub against one another: Friction!
16. Friction The force of friction between the two surfaces can remove electrons from one object and transfer them to another No electrons are lost! They are just moved! The protons and neutrons never move
17. How do we Know Where they Go? But how do we know which surface the electrons are transferred to? We can tell via a measure called electron affinity Electron affinity is the tendency of a substance to hold onto electrons The higher the electron affinity the more likely it is to loose electrons
18. Triboelectric Series
19. How do We Measure This? Charles-Augustine de Coulomb was a French physicist who studied electric charges Closer objects are together the greater the repulsion or attraction Farther the objects are from one another the less the repulsion or attraction
20. Laws of Attraction and Repulsion Have you heard of the saying “opposites attract” The law of attraction states that particles with opposite charges attract to each other The law of repulsion states with like charges repel each other
21. Coulombs (C) In his honour the metric unit for electric charge is in his name sakes Coulomb (C) 1C= 6.24 x 1018 electrons added to or removed from a neutral object So it measures charge
22. Consolidation Activity Quick Lab – Characteristics of Electric Charge Read through lab on page 395 and conduct steps 1-4 with your table group Purpose: To observe the characteristics of electric charge. Conclusion: Answer Q 7-9 in your notebook