This document provides information about static electricity and electrostatics. It defines key terms like electrostatic, charges, protons, electrons, and ions. It discusses historical figures like Benjamin Franklin and his contributions. It explains how charging occurs through friction, conduction, and induction. Rules of attraction and repulsion between charged objects are covered. The document also discusses lightning, electric fields, and Coulomb's Law.

1. Pre AP Physics

2. STATIC
ELECTRICITY
•Electrostatic – the study of electrical
charges that can be collected and held in
one area.
•They flow in no particular direction
(trapped in a body)

3. Electricity of the Atom
 They are ordinarily neutral in charge
 # of protons = # of electrons
 Neutrons = no charge
 Protons = + 1 charge
 Electrons = -1 charge

4. The actual charge of an
electron
-1.60217657 X 10-19
coulombs

5. Little History: Ben Franklin
 Proved lightning was
static electricity
 Invented lightning rod
 Built a static electricity
generator
 Coined the terms
positive and negative
for electrical charge

6. Charged objects
 Atoms become charged by gaining or losing
electrons
 An object that exhibits electrical interaction
after rubbing is said to be
charged

7. Rules of Attraction
Opposite will
attract
Only the electrons will
move
Like will repel
Protons will move but they
don’t leave the nucleus.

8. Interaction between a
charged object and a neutral
object:
 Any charged object (positive or negative) will
have an attraction interaction with a neutral
object.

9. Why are protons never lost or
gained?
 Protons are held in the nucleus by the
strongest forces in the universe.

10. Ions
 Are electrically charged particles
 Charge is unbalanced
 Negative Charge
# e > # p
 Positive charge
# p > # e

11. Neutral State
 Charged objects will eventually return to their
NEUTRAL state
 What/How does this happen?
 The charge “leaks off” onto the water molecules
in the air.
 On humid/rain days it would be difficult to hold a
charge for long.

12. Electro-negativity
Relative
electro-negativity
ranking for some
common materials
from electron
donating
materials (+, glass) to
electron accepting
materials (-,Teflon)
 Glass
 Human Hair
 Nylon
 Silk
 Fur
 Aluminum
 Paper
 Cotton
 Copper
 Rubber
 PVC
 Teflon
+ + + + +
+ + + +
+ + +
+ +
+
-
- -
- - -
- - - -
- - - - -

13. Grounded - neutral
 Charged objects lose their charge when
grounded.

14. "What is the
bottom prong of
a plug called?"
 The bottom prong of a plug is called the
ground.
 It discharges any excess
charge that may develop
in an electrical device

15. When grounded:
 Negatively charged
objects
 .... Lose electrons and
become neutral
 Positively charged
objects
 ... Gain electrons and
become neutral

16. Electroscope
 Used to test the presence of a charged object.

17. If no charge is present,
leaves point straight down.

18. Leaves separate when charge
is present.

19. Where do charges come from?
Rubbing materials does NOT create
electric charges. It just transfers
electrons from one material to the
other.

20. Transfer of charge
 Charge can be transferred between neutral
objects by FRICTION.
 Ex: Rubber rod rubbed with fur or wool will cause
electrons to transfer to the rod
 Rubber Rod gains electrons and becomes negative
 Fur/wool loses electrons and becomes positive

22. +
+
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24. +
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25. +
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26. +
+
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27. +
+
+
+
+
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- -
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+
+
+
+

28. Conduction
 Charging by contact – direct touching
 EX: Conduction with a negative rod

29. How do the electrons flow
during conduction?
 When a negative charged rod comes in
contact with the knob the electrons flow into
the electroscope – charge negative
 When a postive charged rod comes in contact
with the knob the electrons flow into the rod
– charge positive

30. Charging by
Induction

31. Charging by
Induction

32. Induction: The production of a charge
in an uncharged body by bringing a
charged object close to it
When negatively charged rod is put near a metal can...
electrons of the can are pushed
away from the rod.
 top of the can: positive
attraction > repulsion
+
+ + +
+
metal can - -
-
-
-
-
-
-
-
- -
-
buttom of the can: negative
induced
charges attraction
repulsion

33. Attraction of uncharged
objects
Similarly, when charged rod is close to paper scrap..
-
-
-
-
- -
-
molecules of paper align.
 attraction between the rod
and + charge > repulsion
between the rod and - charge.
paper +
–
+
–
+
–
+
–
+
–
+
–
+
–
+
–
attraction
repulsion

34. Electricity, Height, and Women
https://www.youtube.com/watch?v=FGoaXZwF
lJ4&nohtml5=False

35. Static Discharge
Human body can not feel less than
2,000 volts of static discharge
Static charge built up by scuffing
shoes on a carpet can exceed 20,000
volts!

36. Lightning

37. What causes lightning?
 You need cold air
and warm air.
 It is a discharge of
the static electricity
that builds up in
cloud in certain
weather conditions.
 Usually when the
ground is warm and
the air is humid.

38. Interesting facts
 How hot is a lightning bolt? Only about 54,000 degrees Fahrenheit —
roughly five times hotter than the surface of the sun!
 Lightning flashes more than 3 million times a day worldwide — that’s
about 40 times a second. Not all those flashes hit the ground —
some happen between or inside clouds.
 An average lightning bolt can release enough energy to operate a
100-watt light bulb for more than three months straight (about 250
kilowatt-hours of energy).
 Lightning starts in cumulonimbus clouds — aka thunderheads —
which have a positive charge up top and a negative charge below.
We don’t know how the charges start, but water droplets and ice
crystals carry them.

39. Lightning
 Head
straight to
your car
 Move to a
lower
location


40. Electric Fields
 We visualize the field by drawing the
field lines
 Lines point in the same direction as the field.
 Density of lines gives the magnitude of the
field.
 Lines begin on + charges; end on – charges.

41. Field Lines
 Point direction a + charge
would move
 More lines = stronger field

43. Two positive charges..

44. A new force…
Electric force
Between 2 charged objects
Depends on distance and
amt. of charge

45. Coulomb’s Law
F =
qAqB
K
d2
K = 9 x 109 N·m2/C2

46. Coulomb’s Law
Units
Charge - coulomb (C)
Force – Newtons (N)
Distance – meter (m)
Electric force is a vector

47. Van de Graaff Generator
 The globe of the generator builds up excess
electrons through conduction.
 The built electrons are repelling since they
are like charges and we know that like
charges repel so they are spread out as much
as possible.
 The charges are spread out because the globe
is a conductor, unlike electrons that are
rubbed onto the balloon, which stay in the
general area where you rub the balloon.