Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Lets begin with some questions. 1) What is electricity made of? 2) How are static electricity and the electricity found in our homes similar and different? 3) What is electricity's relationship with magnetism? Static Electricity and Charges Magnets, Static Electricity, Electricity, OH MY!! • You are all familiar with magnets, static electricity, and electricity. However did you know that all three are related to one another? • All three (magnets, static electricity, and electricity) are the result of a single property of matter...electric charge. Atoms • The electron is negatively charged. • The proton is positively charged. • The neutron has no charge, it is neutral. Charge • Most things have the same number of electrons and protons in them, and they don’t have any overall charge. • If this isn’t true though interesting things can happen. Gaining Charge – What are atoms made of? – What does a neutral charged atom look like? – What does a positively charged atom look like? – What does a negatively charged atom look like? – What is the only thing that moves in an atom that makes it positively, negatively, or neutrally charged? – Remember protons and neutrons do no move from atom to atom. Its only the electrons. Charge Lets imagine that we have an object that is filled with atoms. Well some of these atoms can have different “charges” based on the number of positive and negative atoms the object will have a positive, negative, or neutral charge. We will draw atoms, just "+" and "–" to illustrate the overall charges Charge We will draw atoms, just "+" and "–" to illustrate the overall charges e.g. a neutral object 5+ 5overall charge 0 Charge We will draw atoms, just "+" and "–" to illustrate the overall charges e.g. a positive object 5+ 3overall charge 2+ Charge We will draw atoms, just "+" and "–" to illustrate the overall charges e.g. a negative object 5+ 8overall charge 3 - What is Static Electricity? Static Electricity: an imbalance of electric charge on the surface of an object. • The object that has got extra electrons is now negatively charged • The object which has lost electrons is positively charged. • Its called static electricity because the charges build up in only one area. What is Static Electricity? Law of Electric Charges: What is Static Electricity? Law of Electric Charges: 1. Opposite charges attract What is Static Electricity? Law of Electric Charges: 1. Opposite charges attract 2. Like charges repel What is Static Electricity? Law of Electric Charges: 1. Opposite charges attract 2. Like charges repel 3. Charged objects attract neutral objects Review • What are atoms made of? • What is the only thing that makes an atom or an object “charged” or neutral? • What does a positively charged atom look like? • Negative? • Neutral? • An object has become positively charged. What has happened? • Negative? Review • Your science teacher has prepared the room for the class's entry by suspending several inflated balloons from the ceiling. Upon entering the science room, you observe two balloons being drawn towards each other. The attraction of these balloons for one another provides evidence that ______. • As you look around the room, you observe two other balloons being pushed away from each other. The repulsion of these balloons from one another provides evidence that ______. Changing Charge • How can we change a charge of an object? – In order to change a charge we need to have electrons move from one object to another. – We can charge objects 3 ways • Friction • Induction • Conduction Friction • Transfer of electrons between the two objects that are rubbed together. • When object A is rubbed against object B the atoms in object A pull the electrons away from object B. • Both objects are now charged. Object A is negative and B is positive. A B Friction • Different materials have different affinities for electrons. Some have a strong affinity (love) for gaining electrons. Others have a lower affinity and easily give off or lose electrons. Triboelectric Series • The materials highest on the table will have the greatest tendency to acquire the negative charge. Those below it would give up their electrons easily and become positively charged. Triboelectric Series Celluloid Sulfur Rubber Copper, Brass Amber Wood Cotton Skin Silk Cat Fur Wool Glass Induction • Charging can occur when materials are not in contact with one another. The build up of charge without direct contact is called induction. • Page 141 Induction Conduction • Charging by conduction involves the contact of a charged object to a neutral object. The neutral object will take on the same charge as the object that it comes in contact with. Conduction Conduction What about the shock? • When an object builds up a large amount of charge it wants to get back to “normal”. It wants to get back to being balanced. • When an object comes close that is either the opposite charge or a neutral charge, the electrons literally jump to the other object. • This is called a static discharge. Once this happens both objects usually return to a neutral state. What about when there is not a shock? • Sometimes we objects can absorb charge and the charge moves to the ground. This is called grounding. • There is no shock because it has moved away from the person/object and into something else. • If the object is “grounded” the charge will be absorbed in the ground and the object/person will have no electrical charge. Static Electricity • • • • What is electricity made of? Why do we call it “static” electricity? How do we build up a charge? What happens when we rub to objects together? • Why does it shock you? • What charge do the objects have after the shock? • What are the law of electric charges? Why not static electricity? • If static electricity and electrical current are the same thing (electrons), why don’t we use it as a power source? – Static electricity is not stable enough to be a continuous or regular source of energy. Potential and Kinetic Energy Remember all forms of energy have kinetic and potential energy. Analogy The electric field is the space around an electrical charge just like a gravitational field is the space around a mass. Electric Field • Space around a charge. What is the difference? Electric Field Lines Electric Field Lines of two Positive Charges Electric Field Lines • Lines that indicate the strength and direction of the electric field. • The more dense the lines, the stronger the field. Which field is stronger? • A B Electrical Potential • Electricity has potential: – This energy comes from the charge particle has due to its position in an electric field. – Because like charges repel, it takes energy to push a charged particle closer to another particle with a like charge. That energy is stored as the electric potential energy. These particles can move and want to/will when it is free to move.