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STATIC ELECTRICITY

STATIC ELECTRICITY. STATIC ELECTRICITY. THE STUDY OF CHARGES AT REST. KEY TOPICS. ELECTRICAL CHARGES COULOMB’S LAW POLARIZATION ELECTRIC FIELD LIGHTNING. ELECTRICAL PHENOMENA. ALL MATTER IS MADE FROM CHARGED PARTICLES

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STATIC ELECTRICITY

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  1. STATIC ELECTRICITY

  2. STATIC ELECTRICITY THE STUDY OF CHARGES AT REST

  3. KEY TOPICS • ELECTRICAL CHARGES • COULOMB’S LAW • POLARIZATION • ELECTRIC FIELD • LIGHTNING

  4. ELECTRICAL PHENOMENA • ALL MATTER IS MADE FROM CHARGED PARTICLES • THE ELECTRICAL PHENOMENA THAT WE EXPERIENCE IS DUE TO THE PRESENCE AND MOVEMENT OF COLLECTIONS OF ELECTRONS

  5. RECOMMENDED ACTIVITY MODEL OF AN ATOM – AIMS Activity

  6. PhET SIMULATION THE PhET SIM CALLED “JOHN TRAVOLTAGE” CAN BE USED TO SHOW HOW WALKING ACROSS A CARPET MIGHT CAUSE YOU TO GET A SHOCK

  7. STATIC ELECTRICITY • WHEN YOU RUB A BALLOON (OR STYROFOAM) ON YOUR HAIR, YOU SCRAPE ELECTRONS FROM THE ATOMS IN THE BALLOON ONTO YOUR HAIR • THE ATOMS IN RUBBER AND STYROFOAM HAVE A STRONGER ATTRACTION FOR SOME OF THE ELECTRONS THAN THOSE IN YOUR HAIR

  8. STATIC ELECTRICITY • RUBBING AN OBJECT MADE OF RUBBER WITH HAIR IS A STANDARD PRACTICE FOR PRODUCING AN OBJECT THAT HAS AN EXCESS OF ELECTRONS • AN OBJECT IN THIS CONDITION POSSESSES AN OVER ALL NET NEGATIVE CHARGE

  9. STATIC ELECTRICITY • OBJECTS CAN POSSESS A NET POSITIVE CHARGE IF THEY LOSE ELECTRONS • OBJECTS CAN HAVE A NET POSITIVE OR NEGATIVE CHARGE IF THEY POSSESS A DEFICIENCY OR AN EXCESS OF ELECTRONS • AN OBJECT IS SAID TO BE NEUTRAL IF THERE IS NO DEFICIENCY OR AN EXCESS OF ELECTRONS

  10. VIDEO TWO STYROFOAM CUPS CAN BE MADE TO REPEL EACH OTHER IF THEY BOTH POSSESS A NET NEGATIVE CHARGE

  11. + - + + “Laws of Attraction” Opposite Charges Attract Like Charges Repel

  12. PhET SIMULATION THE PhET SIM CALLED “ELECTRIC FIELD OF DREAMS” CAN BE USED TO SHOW HOW CHARGED PARTICLES INTERACT LIKE CHARGES REPEL AND UNLIKE CHARGES ATTRACT

  13. A COULOMB • THE FUNDAMENTAL UNIT OF CHARGE • IT IS EQUAL TO THE CHARGE OF 6.25 BILLION BILLION ELECTRONS

  14. COULOMB’S LAW ELECTRICAL FORCE BETWEEN TWO OBJECTS DEPENDS ON THE AMOUNT OF CHARGE ON EACH OBJECT AND THE DISTANCE BETWEEN THE OBJECTS

  15. COULOMB’S LAW • IF THE AMOUNT OF THE CHARGES IS GREATER, THE FORCE IS GREATER • IF THE DISTANCE IS LESS, THE FORCE IS GREATER

  16. VIDEO • A STYROFOAM CUP THAT POSSESSES A NET NEGATIVE CHARGE WILL PICK UP VERY SMALL OBJECTS THAT POSSESS NO EXCESS CHARGE • THIS CAN ONLY BE EXPLAINED BY POLARIZATION

  17. PhET SIMULATION THE PhET SIMULATION “BALLOONS AND STATIC ELECTRICITY” PROVIDES A VERY GOOD DEMONSTRATION OF HOW BALLOONS CAN PICK UP EXCESS ELECTRONS AND THEN EITHER BE REPELLED BY OR ATTRACTED TO OTHER OBJECTS

  18. Polarization • Polarized objects have an uneven distribution of charge. • A polarized object has no net charge. - - - - - - - - - - - - - - - - - - - - - Meter Stick + + + + + + + + + + + + + + + + + + + +

  19. - - - - - - Weak Force - - - - - - - - - - - - - - - - - - - - - + + + + + + + + + + + + + + + + + + + + Strong Force

  20. FORCE AT A DISTANCE • ELECTRICAL, MAGNETIC AND GRAVITATIONAL FORCES UPON OBJECTS HAVE SOMETHING IN COMMON • THESE FORCES CAN BE APPLIED EVEN THOUGH THE OBJECTS INVOLVED ARE AT A DISTANCE FROM EACH OTHER • CHILDREN HAVE A PROBLEM UNDERSTANDING THESE KINDS OF FORCES, BECAUSE THEY EXPECT OBJECTS TO BE IN CONTACT WHEN THEY EXERT A FORCE ON EACH OTHER

  21. GRAVITY THE CONCEPT OF GRAVITATIONAL FIELD IS OFTEN USED TO SHOW HOW THE EARTH CAN EXERT GRAVITATIONAL FORCES ON OBJECTS

  22. ELECTRIC FIELD THE CONCEPT CALL “ELECTRIC FIELD” WAS DEVELOPED TO HELP EXPLAIN HOW OBJECTS WITH ELECTRIC CHARGES CAN HAVE FORCES APPLIED TO THEM

  23. PhET SIMULATION THE PhET SIM CALLED “ELECTRIC FIELD OF DREAMS” CAN BE USED TO SHOW THE ELECTRIC FIELD NEAR A CHARGED PARTICLE THE FIELD POINTS AWAY FROM A POSITIVE PARTICLE AND IS STRONGER NEAR THE PARTICLE

  24. LIGHTNING LIGHTNING IS AN ELECTRICAL DISCHARGE FROM CLOUDS THAT POSSESS A NET CHARGE THE AIR THROUGH WHICH THE DISCHARGE OCCURS IS HEATED AND RAPIDLY EXPANDS TO CAUSE LIGHT AND SOUND

  25. LIGHTNING • CLOUD TO GROUND • THE CLOUD POLARIZES THE GROUND AND THE DISCHARGE OCCURS WHERE THE CHARGE SEPARATION ON THE GROUND IS A MAXIMUM • CLOUD TO CLOUD • IF CLOUDS POSSESS OPPOSITE CHARGES, A DISCHARGE CAN OCCUR BETWEEN THEM

  26. SUMMARY • ELECTRICAL CHARGES • THE ATOM • COULOMB’S LAW • ELECTRICAL FORCES • POLARIZATION • CHARGES ATTRACT NEUTRAL OBJECTS • ELECTRIC FIELD • FORCE AT A DISTANCE • LIGHTNING • CHARGES IN CLOUDS

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