# Electrostatics

Document Sample

```					             Chapter 9
Electrostatics
Sections 9.2, 9.3, 9.4, 9.5, 9.6,
9.7, 9.8, 9.10
9.2 Electrical Nature of Matter
   Static electricity is a natural
phenomena

   The study of static electricity is
elctrostatics.
Continue 9.2
   When two objects are rubbed together,
they can become charged with
electricity. This charge can remain
“static,” which means the charge stays
where the rubbing took place. This is
static electricity.
9.2…
    Law of electric charges:
   like charges repel one another,
   unlike charges attract one another,
   Charged Objects attract neutral object.
    TEST for electric charges
1.    Observe what the object does near an
object with a known charge.
How to test for charges
    We use electroscopes to test for charges.
1.   Observe what the object does near an
object with a known charge. Ex. If you hold a
balloon near a pith ball that you know is
negatively charged and it repels from it
…you would know that the balloon is neg.
2.   Charged objects will attract both opposite
charges and neutral!!
3.   Charged objects will repel like charges!!
9.2 Electrical Nature of Matter
   Ensure you know table 1 p. 273,
“A model for the electrical nature of
matter”
   Complete questions 1, 2, & 3. p. 273
9.3 Charging by Friction
   Charging by friction: transferring an
electric charge from one substance to
another by a rubbing action.
   One objects shares electrons with another.
One is +/ one is -. Think of rubbing a
Electrostatic Series
   Be able to read the electrostatic series and
know its purpose!
   The objects at the top will “give up” some of their
electrons to the ones underneath them. The
greater the distance, the greater the charge is.
   Example: locate hair and plastic on the series.
When you comb your hair(friction) the hair will
give up some of its electrons to the comb. Result:
hair + comb -
Continue 9.3 friction
   HowStuffWorks Videos "Transferring
Charge: Friction“
   Complete questions 1, 2, 3 & 4 p.275
9.5 Transferring Charge by
Contact
   Charging by contact occurs when electric
charge is transferred from one substance to
another because they touch.
   One object shares its charge with another – both
will have the same charge.
   refueling incident
9.6 Insulators and Conductors
   An electrical insulator is a substance in
which electrons cannot move freely from
atom to atom.
   An electrical conductor is a substance in
which electrons can move freely from one
atom to another.
   Insulators & Conductors explained
   Answer 1,2,3, & 4 p.281
9.7 Discharging Electrically
Charged Objects
   Answer 1,2, & 3 p. 283
9.7 Discharging Electrically
Charged Objects
1.   If an object has all excess charges removed,
it is said to be discharged.
2.   When a charged object is grounded to
Earth, it shares its charge with the entire
Earth.
3.   Discharge at a point is a method of
discharging airplanes.
4.   Objects can discharge over time by simple
exposure to air.
9.8 Induction
   Transferring electric charge from one
substance to another without direct contact is
charging by induction.
   The shifting of electrons within a particle due
to a force from another object is induced
charged separation.
   Charging by Induction Video
   Answer 1,2,3, & 4 p. 287
Induction checklist... know:
   object with a charge gets close to a neutral
object - doesn’t touch
   charges it with OPPOSITE charge of charged
object
   usually temporarily charged - when charged
object leaves, electrons redistribute
   cam be permanently charged if connected to a
grounding wire
   be able to illustrate
9.10 Lightning
   Car struck by lightning – BBC