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Unit 3

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Unit 3

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  1. Unit 3 Characteristics of Electricity

  2. Unit 3 • Electrical energy has allowed us to develop technologies that have enhanced our way of life

  3. Hybrid • Hybrid vehicles are often used today where, one part of the vehicle uses a gasoline powered motor and also energy from an electrical motor • As oil prices continue to rise and the environmental concerns are addressed, using electricity for transportation will become even more important

  4. Chapter 7 Static Electricity is produced by electron transfer

  5. Objectives By the end of the lesson you should be able to: • State the 3 Laws of Electrostatics • Describe a Coulomb • Describe how a static charge is created, measured and transferred • Describe insulators and conductors

  6. Physics Intro • Physics: the study of energy and its uses • For this unit we will be focusing on Electrical Energy

  7. Electricity • Electricity is the study of the electron and its uses • Where is electricity used? • Why do we get shocked? • How do light bulbs work? • How does electricity actually flow?

  8. Remember • An atom has 3 subatomic particles Proton Neutron Electron • There are positive and negative charges • Electrons move fairly easily – Proton and neutrons do not! • Add electrons = negative • Remove electrons = positive

  9. Electrostatics • Electrostatics = the study of non-moving electrons • The Laws of Electrostatics: • Opposite charges attract • Like charges repel • Neutral objects are attracted to any charge • An induced charge results from the movement of electrons by charged objects nearby, not by direct contact! • An electroscope measures the amount of static electricity

  10. Static Charge • An excess of positive or negative charges that stay in place on an object for a relatively long period of time. Examples: Lightning, static cling in clothes, receiving a shock when touching a door handle

  11. The Coulomb • Charles Coulomb: lived during the 1700s • Developed a way to measure the quantity of electrons • Named the unit the Coulomb (C) • One C equals 6.25x1018charges Since 1 electron = 1 negative charge 1 C = 6.25 x 1018 electrons!!

  12. Did you know • Lightning contacts the ground at a speed of approximately 220000 km/h

  13. Positive and Negative Charges • Charles Du Fay (1698 – 1739) discovered two types of static electric charges. Benjamin Franklin (1706 – 1790) named the two charges positive (+) and negative (-) charges.

  14. Chemistry Recap • Atoms are made up of protons ( +), neutrons (0), and electrons (-). • # protons = # electrons, the atom is neutral. • Electrons orbit the nucleus and move quite easily. • Movement or transfer of electrons from one atom to another changes the charge on the atom.

  15. A Neutral Atom (Lithium)

  16. Chemistry Recap • When an atom loses electrons, the atom becomes more positive. • When the atom gains electrons, it becomes more negative. • Neutral objects do not have a charge.

  17. Conductors • Allow electrons to transfer freely • Metals are excellent conductors because they can give electrons easily eg. Copper or aluminum

  18. Insulators • Materials that do not allow electrons to move easily from one location on an object to another (electrons tend to stay with the atom they are attached to). Examples: glass, plastics, ceramics, dry wood.

  19. Creating Static Electricity • Friction between two objects causes one object to lose electrons and the other object to gain electrons

  20. Generating Static Charge • Friction causes objects to become charged • For example, the static charge in clouds is produced due to the friction as hot air rises rapidly in the cloud banks • The Van de Graaff generator uses friction to produce a large static charge on a metal dome using a moving belt

  21. Applications • Devices in chimneys use static charge to remove small particles of dust • Plastic sandwich wrap clings use static electricity • Air Ionizers clean the air by attracting charged particles in the air • Static electricity is used in painting automobiles • Refuelling

  22. Dangers of Static Electricity • Before pumping fuel you need to get rid of static electricity because they can cause an explosion • Allowing charge to flow into Earth’s surface is called grounding • Lightning rods on houses and large buildings provide a ground rather than hitting the building