2. Lesson 1
March 2 2012

3. Outline
 Review atomic structure.
 Define electricity
 Charges
 Static Electricity
 Friction
 Insulators and Conductors
 The Triboelectric Series
 Polarization
 Induction
 Conduction
 Grounding

4. Review – Parts of the Atom
Atomic Particles
 Proton
 Positive charge
 Neutron
 No charge
 Electron
 Negative charge

5. Structure of the atom
Can you identify the particles?

6. “Electricity” – which particle
does it sound like?

7. Electricity Electrons
 Electricity is the MOVEMENT of
electrons

8. Why Electrons?
 Protons usually don’t move
 They are stuck in the nucleus with the
neutrons
 Electrons ORBIT around the nucleus
 They can be moved out of their orbits, away
from the nucleus

9. Charge
 CHARGE is the measurement of EXTRA
PROTONS or EXTRA ELECTRONS an
object has.
 A POSITIVELY CHARGED object has
MORE PROTONS than electrons.
 A NEGATIVELY CHARGED object has
MORE ELECTRONS than protons.

10. Separating Charges
What do we mean when we say
“separating charges?”
Remember: Electricity is the MOVEMENT of
ELECTRONS

11. Separating Charges cont.
 Atoms usually have the same number of
PROTONS ( + positive charge) and
ELECTRONS ( - negative charge)
 The positive and negative charges balance, so the
atom has a NEUTRAL CHARGE
 ADDING or REMOVING electrons changes
the charge of the atom
 ADDING electrons makes the charge NEGATIVE
 REMOVING electrons makes the charge POSITIVE
This is what we mean when we say “separating
charges.”
*A charged atom is called an ION

12. Separating Charges cont.
How Do We Separate
Charges?
 How can we move electrons from one
place to another?
 FRICTION is one way to separate
charge.
 What is FRICTION?

13. Separating Charges cont.
Friction
 FRICTION is rubbing two objects together.
 When two objects are rubbed together,
some electrons move from one object to
the other object.
 This separates the charges of the atoms in
the surfaces of the objects.
 The surface of one object becomes
POSITIVELY charged, and the surface of
the other object becomes NEGATIVELY
charged.

14. Static Electricity
 When electrons are moved from one object
to another object by friction, STATIC
ELECTRICITY is the result
 STATIC (adj) = stays in one spot
 Once the charge has moved from one object to
the other, it stops moving.

15. Static Electricity cont.
Insulators and Conductors
 Materials like glass, plastic, rubber, and
wood are good at collecting electrons in
a static charge.
 These materials are called INSULATORS
 Materials like metal and water are NOT
good at collecting electrons in a static
charge.
 These materials are called CONDUCTORS
 (MORE ON THIS LATER)

16. Static Electricity cont.
 Once electrons have been transferred
from one object to another, we can say
one object is POSITIVELY CHARGED
and the other object is NEGATIVELY
CHARGED.
 What do OPPOSITELY CHARGED
PARTICLES do?

17. Static Electricity cont.
EXPERIMENT!
 What does the balloon ATTRACT?
 What does it REPEL?

18. Static Electricity
Experiment Results
 The balloon was NEGATIVELY charged,
so it ATTRACTED anything with a
POSITIVE charge
 It REPELLED anything with a
NEGATIVE charge.
 This illustrates the LAW OF CHARGES!

19. Law of Charges

20. …but what about neutral
charges?
 Neutrally charged objects (objects with
no charge) are attracted to objects with
POSITIVE and NEGATIVE charges.
 More on this later!

21. The Triboelectric Series
 Some materials are better at holding
onto electrons, and some materials are
better at giving away electrons.
 The TRIBOELECTRIC SERIES ranks
materials based on their affinity for
electrons.

22. Triboelectric Series cont.
 ALL materials fall somewhere on the
triboelectric series.
 Example using a few different materials:
Materials at the TOP of the list
gather more electrons than those
at the bottom.

23. Law of Conservation of Charge
Charge is only transferred. It just moves
between objects.

24.  Both the copper and the glass have
NEUTRAL CHARGE.
 They each have 6 units of electrons.
 What happens if you rub them together?
COPPER GLASS
6e 6e

25. Using the triboelectric series, we see that
copper gathers more electrons than glass.
Using the Law of Conservation of Charge, we
see that the total charge between the two
stays the same.
COPPER 2e GLASS
8e 4e

26.  The glass loses 2 units of electrons, and
so it now has a positive charge.
 The copper gains those 2 units of
electrons, and so it now has a negative
charge.

27. Conductors and Insulators
 CONDUCTORS let electrons to flow
easily between atoms, or between
molecules.
 INSULATORS do not let electrons flow
easily between atoms, or between
molecules.
 Can you remember some examples of
conductors and insulators?

28.  CONDUCTORS
 Metals, carbon, water, people?!
 INSULATORS
 Rubber, wood, glass

29. Conductors
 When a charge is transferred to an
object made from a conductive material,
the charge spreads through the object.

30. Insulators
 When a charge is transferred to an
object made from an insulating material,
the charge does not move.
 This is why insulators are good for
demonstrating static electricity. Static = does
not move

31. Conductors vs. Insulators
 Conductors have an atomic structure
that lets electrons move in a clear path.
 Insulators have an atomic structure that
does not allow electrons to move in a
clear path.

32. Polarization
sdf

33. Polarization
 Polarization means to separate into
opposites.
 When a charged object is placed on an
oppositely charged (or neutrally
charged) object, both objects will
become polarized.
 This means that their opposite sides will
have opposite charges.