Electricity

1. Electricity

2. Atoms Are Everywhere • Electrons move in and out of fixed pathways around the nucleus • Changing the number of electrons in a particular type of atom creates an ion of that atom

3. Atoms… • Have neutrons, protons, and electrons. • Protons are positively charged • Electrons are negatively charged

4. On the Move • Electrons in the outer rings or shells of atoms are bound more loosely to the nucleus • Such electrons tend to break free from the nucleus and wander around amongst other nearby atoms • Such electrons are called free electrons

6. Electrons… • Are located on the outer edges of atoms…they can be moved. • A concentration of electrons in an atom creates a net negative charge. • If electrons are stripped away, the atom becomes positively charged.

7. Current = Conduction • Such movement of these free electrons creates an electric current • Materials with large numbers of free electrons are called electrical conductors. They conduct electrical current. • Movement of the electrons physically from one place to another is slow. Transfer of the energy from one electron to another happens fast.

10. The world is filled with electrical charges: + - + + + - + - - + + + - - - + + - - -

11. What is this electrical potential called? • Static Electricity - - - - - + + + - - + +

12. Static Electricity • The build up of an electric charge on the surface of an object. • The charge builds up but does not flow. • Static electricity is potential energy. It does not move. It is stored.

14. Static Discharge… • Occurs when there is a loss of static electricity due to three possible things: • Friction - rubbing • Conduction – direct contact • Induction – through an electrical field (not direct contact)

15. Conduction (direct contact) FRICTION (RUBBING THE BALLON ON THE HEAD Induction (no direct contact)

17. Electricity that moves… • Current: The flow of electrons from one place to another. • Measured in amperes (amps) • Kinetic energy

18. What is “Electricity”? - "Electricity" means electric charge. Examples: CHARGES OF ELECTRICITY. COULOMBS OF ELECTRICITY. - "Electricity" refers to the flowing motion of electric charge. Examples: CURRENT ELECTRICITY. AMPERES OF ELECTRICITY. - "Electricity" means electrical energy. Examples: PRICE OF ELECTRICITY. KILOWATT-HOURS OF ELECTRICITY. - "Electricity" refers to the amount of imbalance between quantities of electrons and protons. Example: STATIC ELECTRICITY. - "Electricity" is a class of phenomena involving electric charges. Examples: BIOELECTRICITY, PIEZOELECTRICITY, TRIBOELECTRICITY, THERMOELECTRICITY, ATMOSPHERIC ELECTRICITY ...ETC.

19. Electricity? • Electricity is all about electrons, which are the fundamental cause of electricity • Static Electricity - involves electrons that are moved from one place to another, usually by rubbing or brushing • Current Electricity - involves the flow of electrons in a conductor

20. Electric Charge • Two kinds: positive and negative (terms coined by Benjamin Franklin) • When you rub a glass rod with silk, the charge that is left on the glass was called positive. If you rub a hard rubber rod with silk, the charge left on the rod was called negative. • Like charges repel while unlike charges attract.

21. Conductors vs. Insulators • Conductors – material through which electric current flows easily. • Insulators – materials through which electric current cannot move. Activity on insulator and conductors!!! http://www.andythelwell.com/blobz/guide.html

24. Conductors: Metal Water Insulators: Styrofoam Rubber Plastic Paper Examples

25. Conductors and Insulators • In conductors, electric charges are free to move through the material. In insulators, they are not. • In conductors: • The charge carriers are called free electrons • Only negative charges are free to move • When isolated atoms are combined to form a metal, outer electrons of the atoms do not remain attached to individual atoms but become free to move throughout the volume of the material

26. GRAPHITE?

27. PLASTIC?

28. CONCRETE?

29. AIR MOLECULES?

30. SILVER?

31. DIAMOND?

32. RUBBER?

33. PURE WATER?

35. GOLD?

36. There are 2 types of currents: • Direct Current (DC) – Where electrons flow in the same direction in a wire.

37. There are 2 types of currents: • Alternating Current (AC) – electrons flow in different directions in a wire

38. Know Your Symbols • Battery or Power Supply • Resistor • Capacitor • Switch • Conductive Wire

39. There are 2 types of circuits: • Series Circuit: the components are lined up along one path. If the circuit is broken, all components turn off.

40. Series Circuit

41. Series Circuits • An electrical circuit with only one path for the electrical current to follow

42. There are 2 types of circuits: • Parallel Circuit – there are several branching paths to the components. If the circuit is broken at any one branch, only the components on that branch will turn off.

43. Parallel Circuit

44. WHAT IS ELECTRIC CURRENT?

46. It is nothing but the rate of flow of electrons in the conductor per second.

47. I= Q t Where I is the electric current in amps Q is the charge in coulombs and t is the time in seconds.

48. What is Resistance? • The opposition to the flow of an electric current, producing heat. • The greater the resistance, the less current gets through. • Good conductors have low resistance. • Measured in ohms.

49. What Influences Resistance? • Material of wire – aluminum and copper have low resistance • Thickness – the thicker the wire the lower the resistance • Length – shorter wire has lower resistance • Temperature – lower temperature has lower resistance

50. What is Voltage? • The measure of energy given to the charge flowing in a circuit. • The greater the voltage, the greater the force or “pressure” that drives the charge through the circuit.