Charging and Discharging Objects

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Charging and Discharging Objects

  1. 1. Charging and Discharging Objects
  2. 2. <ul><li>An electroscope is a device that allows you to test whether an object is charged </li></ul><ul><li>The main parts of an electroscope are a metal ball , a metal rod and metal leaves </li></ul>Electroscopes metal ball metal rod metal leaves
  3. 3. <ul><li>The ball, rod and leaves are all conductors </li></ul><ul><li>Conductors allow electrons to move easily through them </li></ul>Electroscopes metal ball metal rod metal leaves
  4. 4. Electroscopes <ul><li>When the electroscope is neutral , the leaves stay together </li></ul>+ - + - + - + - + + - + - + - + - + - + - + - + - + - + - + - + - + - - + -
  5. 5. Electroscopes <ul><li>When the electroscope is positively or negatively charged , the leaves repel each other (separate) </li></ul>+ - + - + - - - - - - - - - - - - - - + - + - + - + + + + + + + + - + -
  6. 6. <ul><li>When a neutral object is touched by a charged object, some of the charge transfers to the neutral object and the neutral object becomes charged . </li></ul>Charging By Contact <ul><li>- - - - - - - - - - </li></ul><ul><li>- </li></ul><ul><li>- - - - - - - - - </li></ul><ul><li>- - - - - - - </li></ul><ul><li>- - - - - - - </li></ul>- - - - -
  7. 7. <ul><li>When a negatively charged object touches a neutral object, electrons move to the neutral object making it negative </li></ul>Charging By Contact <ul><li>- - - - - - - - - - </li></ul><ul><li>- </li></ul><ul><li>- - - - - - - - - </li></ul><ul><li>- - - - - - - </li></ul><ul><li>- - - - - - - </li></ul>- - - - - ebonite rod
  8. 8. <ul><li>When a positively charged object touches a neutral object, electrons move from the neutral object to the positive object and make the neutral object positive </li></ul>Charging By Contact + + + + + + + + + + + + + + + + + + - + - + - + + + + - - + - + - + - + - + + + + + + + + - - - - acrylic rod
  9. 9. <ul><li>When an insulating material is charged by contact, the charge stays on the insulator at the point where it is touched </li></ul>Charging By Contact
  10. 10. <ul><li>When a conducting material is charged by contact, the charge spreads out over the whole surface of the conductor. </li></ul>Charging By Contact
  11. 11. <ul><li>Induction is the movement of electrons within a substance, caused by a nearby charged object, without direct contact </li></ul>Induction
  12. 12. <ul><li>If you rub a rubber balloon on your hair, electrons will transfer from your hair to the balloon, making the balloon negative </li></ul>Induction
  13. 13. <ul><li>When you bring the negatively charged balloon near a neutral wall, the electrons on the balloon repel the negative charges on the wall, making that part of the wall positive </li></ul>Induction
  14. 14. <ul><li>The balloon is said to induce a charge on the wall because it charges the wall without contacting it </li></ul>Induction
  15. 15. <ul><li>Grounding is the process of connecting a charged object to the Earth’s surface </li></ul>Grounding (Symbol for grounding)
  16. 16. <ul><li>When you connect a charged object to the ground, you provide a path for charges to travel to or from the ground </li></ul>Grounding
  17. 17. <ul><li>When you charge an object by induction , you use a charged object to induce a charge in a neutral object </li></ul><ul><li>Then you ground the newly charged object so that it retains the charge </li></ul>Charging By Induction
  18. 18. Charging By Induction <ul><li>Step 1 : </li></ul><ul><li>When a negatively charged object comes near a neutral electroscope, it repels the electrons in the neutral electroscope </li></ul>
  19. 19. Charging By Induction <ul><li>Step 2 : </li></ul><ul><li>When you ground the neutral electroscope, you provide its electrons with a path away from the repulsive influence. Some electrons leave the electroscope. </li></ul>
  20. 20. Charging By Induction <ul><li>Step 3 : </li></ul><ul><li>When you remove the ground and the charged object, the electroscope is left with a positive charge because it has lost some electrons </li></ul>
  21. 21. Charging By Induction <ul><li>Step 1 : </li></ul><ul><li>When a positively charged object comes near a neutral electroscope, it attracts the electrons in the neutral electroscope </li></ul>
  22. 22. Charging By Induction <ul><li>Step 2 : </li></ul><ul><li>When you ground the neutral electroscope, you provide a path for electrons to go toward the positive influence. </li></ul>
  23. 23. <ul><li>Step 3 : </li></ul><ul><li>When you remove the ground and the charged object, the electroscope is left with a negative charge because it has gained some electrons </li></ul>Charging By Induction
  24. 24. <ul><li>Once an object is charged , the charges are trapped on it until they are given a path to escape </li></ul><ul><li>When electric charges are transferred very quickly , the process is called an electrical discharge </li></ul>Electrical Discharge
  25. 25. <ul><li>Sparks are an example of electric discharge </li></ul>
  26. 26. <ul><li>Lightning is an example of a very large electrical discharge caused by induction </li></ul>Electrical Discharge
  27. 27. Lightning
  28. 28. Lightning <ul><li>Lightning can strike up to 15km from where it is raining </li></ul><ul><li>If you can hear thunder , you are in striking distance </li></ul><ul><li>Safe shelter includes large buildings or vehicles (provided the windows are rolled up and you do not touch metal parts of the vehicle) </li></ul>
  29. 29. Lightning <ul><li>Avoid the highest point of land (e.g. under a tree) because lightning tends to strike these areas </li></ul><ul><li>Stay away from objects that conduct electricity (e.g. bicycles, golf clubs, lawn mowers etc.) </li></ul>

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