Question of the Day Rules  You must work alone  You may use your textbook today  You have 6 minutes to complete the QOD Good luck!!

Read page 176/177 of the textbook 1) Briefly explain how a wind turbine can generate electricity using wind energy. 2) Do you think it would be a good idea to build wind turbines in your region? Explain your answer, suggesting at least two advantages and two disadvantages.

Answer 1) Briefly explain how a wind turbine can generate electricity using wind energy. ANSWER: The wind turns the blades of the turbine, which transforms mechanical energy into electrical energy.

2) Do you think it would be a good idea to build wind turbines in your region? Explain your answer, suggesting at least two advantages and two disadvantages. Advantages: Once built, it is a clean energy source, wind is free Disadvantages: The wind is unpredictable. – In the city, there is not enough space to build turbines. – In the country, the towers ruin the beauty of the landscape.

What are we doing Today? Chapter 5  QOD  Notes on Chapter 5  Chapter 4 (EST) Test Wednesday  Video Project  Classwork

Video Project  Due this Friday, December 19 th, 2014  If you know you will not be there, you should hand it in before that day to not lose marks  Make sure your video plays on a school computer before you submit it to me.  Make sure you and your partners names are on everything  Read through the rubric carefully for full marks

Electricity & Magnetism

What Is Electricity?  All phenomena caused by positive and negative charges

Electric Charge  All matter is made up of atoms  Atoms contain 1. Protons (+) 2. Neutrons (0) 3. Electrons (-)

Law of Electric Charges  The law of electric charges states that like charges repel, and opposite charges attract.  Protons are positively charged and electrons are negatively charged, so they are attracted to each other.

Law of Electric Charges

Electric Force The force between the charged objects is an electric force. The size of the electric force depends on 2 things: 1. The amount of charge (the greater the charge, the greater the force) 2. The distance between charges (the further the distance, the less the force)

Electric Field  An electric field is the region around a charged object where electric forces can be exerted on another charged object. (Repelled or attracted)

Electric field lines point away from positive charges & towards negative charges

Charged Objects  Atoms do not have a charge because the number of electrons and protons cancel each other out. Ex. 3 protons (+) & 3 electrons (-) = 0

Charged Objects How do objects get charged?  They either gain or lose electrons.  Why not protons? Ex. 3 protons (+) & 5 electrons (-) = 7 protons (+) & 2 electrons (-) =

Unit of Measurement The Elementary Charge is the charge carried by a single electron or proton. Its value is x C C is Coulomb. It is the measurement for electrical charge. 1 Coulomb = 6.25 x electrons or protons

How Can You Charge Objects?  There are 3 ways objects can be charged: 1. Friction 2. Conduction 3. Induction **In each of these, only the electrons move. The protons stay in the nucleus**

Friction  Charging by friction occurs when electrons are “wiped” from one object onto another. Ex. If you use a cloth to rub a plastic ruler, electrons move from the cloth to the ruler. The ruler gains electrons and the cloth loses electrons.

The TriboElectric Series  When two different materials are pressed or rubbed together, the surface of one material will generally steal some electrons from the surface of the other material.

Triboelectric Series p.146 – Table 5.14  If you rub a glass rod against silk. Which of the substances gets a negative charge? Silk acquires a negative charge Glass acquires a positive charge

Conduction  Charging by conduction happens when electrons move from one object to another through direct contact (touching). Ex. Suppose you touch an uncharged piece of metal with a positively charged glass rod. Electrons from the metal will move to the glass rod. The metal loses electrons and becomes positively charged.

Induction  Charging by induction happens when charges in an uncharged object are rearranged without direct contact with a charged object. Ex. If you charge up a balloon through friction and place the balloon near pieces of paper, the charges of the paper will be rearranged and the paper will be attracted to the balloon.

Induction : The production of a charge in an uncharged body by bringing a charged object close to it When negatively charged rod is put near a metal can... electrons of the can are pushed away from the rod.  top of the can: positive & attraction > repulsion metal can buttom of the can: negative induced charges attraction repulsion

Conservation of Charge  When you charge something by any method, no charges are created or destroyed.  The numbers of electrons and protons stay the same. Electrons simply move from one atom to another.

Conductors and Insulators  An electrical conductor is a material in which charges can move easily.  Most metals are good conductors because some of their electrons are free to move.  Conductors are used to make wires. For example, a lamp cord has metal wire and metal prongs.

Conductors and Insulators  An electrical insulator is a material in which charges cannot move easily.  Insulators do not conduct charges very well because their electrons cannot flow freely.  The insulating material in a lamp cord stops charges from leaving the wire and protects you from electric shock.  Plastic, rubber, glass, wood, and air are good insulators.

Static Electricity  Static electricity is the electric charge at rest on an object.  When something is static, it is not moving.

Electric Discharge  The loss of static electricity as charges move off an object is called electric discharge.

Class Work  (Chapter 5) Read pages of the Textbook and complete Questions: 1-5 of the textbook