Static Electricity

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Static Electricity

  1. 1. Static Electricity
  2. 2. <ul><li>all matter is made of atoms </li></ul><ul><li>atoms contain smaller particles: protons , neutrons and electrons </li></ul><ul><li>some of these particles have an electric charge: </li></ul>Atomic Structure & Electric Charge
  3. 3. orbiting the nucleus negative (-) electron nucleus no charge (0) neutron nucleus positive (+) proton Location Electric Charge Particle
  4. 4. <ul><li>If an object has more electrons than protons, it is negatively charged. </li></ul>Electric Charge # protons: 8 # electrons: 12 # protons < # electrons therefore, overall charge = negative
  5. 5. <ul><li>if an object has more protons than electrons, it is positively charged </li></ul>Electric Charge # protons: 8 # electrons: 5 # protons > # electrons therefore, overall charge = positive
  6. 6. <ul><li>If an object has an equal number of protons and electrons, the object is neutral </li></ul>Electric Charge # protons: 8 # electrons: 8 # protons = # electrons therefore, overall charge = neutral
  7. 7. Electric Charge + — Law of attraction: opposite charges attract
  8. 8. Electric Charge Law of repulsion: like charges repel + — + —
  9. 9. Electric Charge A charged object and a neutral object will attract each other 0 0 + —
  10. 10. <ul><li>Electrons can be transferred from one object to another. </li></ul><ul><li>For example, a neutral or positively charged object will become negatively charged if it gains electrons. </li></ul>Electric Charge
  11. 11. <ul><li>Similarly, a neutral or negatively charged object will become positively charged if it loses electrons. </li></ul>Electric Charge
  12. 12. <ul><li>Only electrons (negative charges) are capable of moving from one object to another! </li></ul><ul><li>Protons ( positive charges) stay in place. </li></ul>Electric Charge
  13. 13. <ul><li>Different substances have different abilities to hold on to electrons </li></ul><ul><li>the tendency of a substance to hold on to the electrons is called electron affinity </li></ul>Electron Affinity
  14. 14. Electron Affinity human skin rabit fur acetate glass human hair nylon wool cat fur silk paper cotton wood amber rubber balloon vinyl polyester ebonite + - tendency to lose electrons tendency to gain electrons
  15. 15. <ul><li>Conductivity is the ability of materials to allow electrons to move freely </li></ul><ul><li>Materials that hold on to their electrons and do not allow them to move easily are called electrical insulators </li></ul><ul><li>Materials that allow electrons to change positions are called conductors </li></ul>Conductors & Insulators
  16. 16. Insulators In an insulator, the electrons (-) are bound tightly to the nuclei (+) so they resist movement + — + — + — + — + — + — + —
  17. 17. Common Insulators
  18. 18. Conductors In a conductor, the electrons are not as tightly bound to the nuclei and can therefore move away from the nuclei + — + — + — + — + — + — + —
  19. 19. Common Conductors
  20. 20. <ul><li>The electric charge that builds up on the surface of an object is called a static charge </li></ul><ul><li>The charges are “static” because they remain in one location on the surface of the object until they are given a path to escape </li></ul>Static Electricity
  21. 21. Static Electricity and Friction <ul><li>All solid materials are charged by the transfer of electrons </li></ul><ul><li>When two objects rub together, the force of friction can remove electrons from one object and transfer them to the other object </li></ul>
  22. 22. <ul><li>As one object loses electrons, the other object gains them </li></ul>Static Electricity and Friction
  23. 23. <ul><li>New electrons are not being created , they are just being rearranged </li></ul>Static Electricity and Friction
  24. 24. Static Electricity

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