Electricity

1. Electricity

2. Electrostatics • The branch of physics that deals with stationary charges

3. You walk across the rug, reach for the doorknob and..........ZAP!!! You get a static shock.

4. Or, you come inside from the cold, pull off your hat and......static hair!! • The static electricity makes your hair stand straight out from your head.

5. WHY? • Everything we see is made up of tiny little parts called atoms. • The atoms are made of even smaller parts. These are called protons, electrons and neutrons. • They are very different from each other in many ways.

6. One way they are different is their "charge." • Protons have a positive (+) charge. • Electrons have a negative (-) charge. • Neutrons have no charge.

7. Static Electricity • Usually, atoms have the same number of electrons and protons. Then the atom has no charge, it is "neutral.“ • But if you rub things together, electrons can move from one atom to another. • Some atoms get extra electrons. They have a negative charge. Other atoms lose electrons. They have a positive charge. • When charges are separated like this, it is called static electricity.

8. Static Electricity • Example: • Object A and B are both neutral. If an electron moves from object A to object B, Object A becomes positively charged and object B becomes negatively charged

9. Electrostatics • Glass and Silk • positive glass and negative silk • Amber/Rubber and Fur • Negative amber/rubber and positive fur • Which way are the electrons moving? • Glass and silk- From the glass to the silk • Rubber and Fur- From the Fur to the Rubber

11. Electricity • Electric Charge (q) • Positive and Negative Charges • Unit: Coulomb (C) • Charge Transfer • Charge can be transferred from one object to anotherbut can never be created or destroyed Conservation of Charge

12. Opposite charge attract • Like charges repel

13. Why do electrons move from one object to another? • Electrons are all negatively charged, so they repel each other. • If the electrons are closer together in one object, they will want to move to the other object to spread out. Example: Think of two classrooms connected by a door. One room has 50 students inside, the other has 10. If the teacher let the students move around, you would probably end up with equal numbers students in both rooms…just like electrons.

14. So, why does your hair stand up after you take your hat off? • When you pull your hat off, it rubs against your hair. Electrons move from your hair to the hat. • Now each of the hairs has the same positive charge. • Things with the same charge repel each other. So the hairs try to move away from each other. • The farthest they can get is to stand up and away from all the other hairs. Balloon Simulation

15. Why do you feel a shock when you wear socks on the carpet and touch a doorknob? • When you walk around in socks, they rub against the carpet and electrons move from the carpet to you. When you touch the doorknob, all the extra electron moves away from you and into the knob.

16. Electroscopes • a device used to detect the presence of charge • usually constructed with a metal plate or sphere at the top of a metal post with thin foil leaves hanging from the bottom of the post. Electroscope Webquest Electroscopes

17. Van der Graaf Generator • Machine that produces static charge Bill Nye Van der Graaf

18. Electric Field Negative Gravity? Think Gravity

19. Electric Fields • A field generated by a charge • A force exerted on a small charge placed in the field • The direction of the electric field, is in the same direction a positive point charge would travel if placed at that location. Electric Field Hockey

20. What is the difference?

21. Electric Field Lines

22. The larger the charge on an object, the greater the electric field • The further you get from the charge, the smaller the electric field will be Electric Field Hockey

25. Videos Static Electricity How lightning forms How Lightning works Best Lightning Strikes