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1.4 The motor generator Sandia national lab - fusion device that makes electrons arc across the room.

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Presentation on theme: "1.4 The motor generator Sandia national lab - fusion device that makes electrons arc across the room."— Presentation transcript:

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7 1.4 The motor generator

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10 Sandia national lab - fusion device that makes electrons arc across the room

11 Where does Electricity come from?

12 Electricity is a form of energy produced by the movement of electrons from atom to atom. E lectrons tend to stay put in their orbits (or "shells") as long as the atom has the same number of positively charged protons and negatively charged electrons. When something upsets this balance, electrons leave their orbits and become "free electrons."

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20 Electricity = Electrons

21 All matter is made up of very small particles called atoms. Atoms are made of even smaller particles called protons, neutrons, and electrons

22 Part of the Atom proton 1 amu+1 Neutron 1 amu0nucleus electron 0 amuelectron cloud mass Charge Location nucleus

23 What is the Law of Electric Charges ?

24 Law of Electric Charges Charged objects exert a force- a push or pull- on other charged objects. The law states that like charges repel each other and opposite charges attract each other

25 What is Electric Force? What does electric force depend on? Page 5

26 Electric force The force between charged objects The size of the electric force depends on two things. The first thing is the amount of charge on each object. The greater the charge is, the greater the electric force is. The other thing that determines the size of the electric force is the distance between the charges. The closer together the charges are, the greater the electric force is.

27 What is an electric field?

28 E lectric field t he region around a charged object in which an electric force is exerted on another charged object. A charged object in the electric field of another charged object is attracted or repelled by the electric force acting on it.

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30 Why are you NOT getting a shock by every object around you if protons and electrons are charged objects?

31 Charge Atoms have equal numbers of protons and electrons. Because an atom’s positive and negative charges cancel each other out, atoms do not have a charge. An object becomes positively charged when it loses electrons. An object becomes negatively charged when it gains electrons.

32 Friction two objects rub against one another. One object absorbs electrons from the other making both objects charged and attracted to each other.

33 Conduction Electrons move from one object to another by direct contact

34 Induction when charges in an uncharged metal object are rearranged without direct contact with a charged object.

35 Give a brief summary of the three types of electrical transfer.

36 What is the Law of Conservation of Charges?

37 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, which makes areas that have different charges. Because charges are not created or destroyed, charge is said to be conserved. `

38 What are the energy conversions here? http://www.youtube.com/watch?v=MTKXXbbiqRs&feature=related

39 What's the best way for electricity to move from one place to another?

40 Electrical conductor a material in which charges can move easily. Most metals are good conductors because some of their electrons are free to move copper

41 How do you prevent the electrical conductor wires in your house from conducting electricity into the house starting a fire?

42 Electrical Insulator A material in which charges cannot easily move. Insulators do not conduct electricity because their electrons do not flow freely. Plastic is one of the best insulators. All cords and wires in your house are wrapped on plastic. plastic coating

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44 These jumper cables are made of metal, which carries electric charges, and plastic, which keeps the charges away from your hands.

45 Explain Static Electricity. ( page 8 )

46 Static electricity the electric charge at rest on an object. http://www.youtube.com/watch?v=uVVJZhUXZaY&feature=related Static means not moving. The charges build up on an object and stay there until an opposite charge gets within the charges field.

47 What is an electric discharge?

48 Electric Discharge Charges that build up as static electricity on an object eventually leave the object. The loss of static electricity as charges move off an object

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50 What are the dangers of Lightning? how do we protect houses and buildings from lightning?

51 Lightning Rods http://www.youtube.com/watch?v=jiKNisWj-Hs

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53 Section 2 An electric current is the rate at which charges pass a given point. The higher the current is, the greater the number of charges that pass the point each second. Electric current is expressed in units called Amperes (AM PIRZ), which is often shortened to amps.

54 Andre Ampere - French 1775-1836 The symbol for ampere is A. And in equations, the symbol for current is the letter I.

55 What are the two types of electric current?

56 There are two kinds of electric current—direct current (DC) and alternating current (AC). In direct current, the charges always flow in the same direction. In alternating current, the charges continually shift from flowing in one direction to flowing in the reverse direction. The average home has AC current that changes direction 120 times/second, or 60 cycles per second

57 Luigi Galvani - Italian

58 Voltage is the potential difference between two points in a circuit. It is expressed in volts (V). Voltage and Energy Voltage is a measure of how much work is needed to move a charge between two points. You can think of voltage as the amount of energy released as a charge moves between two points in the path of a current. The higher the voltage is, the more energy is released per charge. Voltage of electricity always flows from where there is a lot of electricity to where there is less electricity.

59 An electric eel can create a voltage of more than 600 V! Electric Ray @ 45 V

60 Resistance the opposition to the flow of electric charge. Resistance is expressed in Ohms (Ω, the Greek letter omega). In equations, the symbol for resistance is the letter R. You can think of resistance as “electrical friction.” The higher the resistance of a material is, the lower the current in the material is. So, if the voltage doesn’t change, as resistance goes up, current goes down. An object’s resistance depends on the object’s material, thickness, length, and temperature.

61 Resistance and Material Good conductors, such as copper, have low resistance. Poor conductors, such as iron, have higher resistance. The resistance of insulators is so high that electric charges cannot flow in them. Materials with low resistance, such as copper, are used to make wires. But materials with high resistance are also helpful. For example, the high resistance of the filament in a light bulb causes the light bulb to heat up and give off light.


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