1. Electrostatics

2. Electrostatic Also called Static Electricity
The structure of matter is the atom.
All matter is made of atoms.
Atoms are known as elements
Elements can combine to form compounds.
Because everything is made of atoms, everything has a an electrical property.

3. What does an Atom look like?

4. What are the parts of an atom?
Protons
In the nucleus
Strong bond
positive
Neutrons
No charge
Electrons
Outside nucleus
Weak bond
Negative charge

5. Charge
There are two kinds of charges
Positive
Negative

6. Charge
Electrons are negatively charged
Protons are positively charged

7. Charge Like charges repel Example: protons repel protons
Unlike Charges attract
Example: Protons attract electrons

8. What causes something to be charged?
The number of electrons dictate if something has a charge.
If P=E, then it is electrically neutral.
If P=E, the it is electrically charged. It is now called an ion and not an atom.
If P>E, positively charged.
If P<E, negatively charged

9. Charge Electric Charge is quantized (it has a value).
An electron has a charge of
-1.6 x C
C=Coulomb.

10. Charge Electric charge is conserved
Charges can be transferred, but or not created nor destroyed

11. Charged + Neutral
A charged object (Positive or negative) will attract a neutral object.
Positive and neutral attract each other.
Negative and neutral attract each other.

12. Transfer of Charge Conductors
Conductor: material that transfers charge easily. Electrons are not held tightly to the nucleus so they are distributed across the surface of the object.

14. Examples of Conductors
Metals
Pots and pans when you conduct move heat energy
Copper wire allows movement of electrons to charge your phone
Human body

15. Transfer of Charge Insulators
Insulators: a material that does not transfer charge easily.
Insulators hold their electrons more tightly.
A poor conductor of electricity.
If charge is transferred to an insulator, the excess charge will remain at initial location of charging.

16. Examples of Insulators
Plastic,
Styrofoam
Paper
Rubber
Glass
Dry air

17. One is copper and one is rubber. Which is which?

18. Transfer of Charge Polarization
When a charged object is brought next to a neutrally charged insulator, polarization occurs.

19. Transfer of Charge Polarization
Polarization: The presence of a charged object will cause another object’s charges to realign. One side of the object will be more positive and the other more negative.

21. Which diagram correctly depicts polarization?

22. In this situation, the conducting sphere is…..
Charged
Uncharged
Polarized

23. Law of conservation of Charge
Electrons always come from somewhere.
They are not created from nothing.
Electrons are acquired from somewhere.
Charge is conserved. The electrons move somewhere else

24. Transfer of Charge Charging by Contact
Also called charging by friction.
The transfer of electrical charges by objects in contact.

25. A plastic strip was rubbed with cotton and became positively charged
A plastic strip was rubbed with cotton and became positively charged. Why?
A. Plastic strip acquired extra protons from the cotton.
B. The plastic strip acquired extra protons during the charging process.
C. Protons were created as the result of the charging process.
D. The plastic strip lost electrons to the cotton during the charging process.

26. Saran Wrap has a larger electron affinity than Nylon
Saran Wrap has a larger electron affinity than Nylon. If nylon is rubbed against Saran Wrap, which would end up with the excess negative charge?

27. Transfer of Charge Induction
Induction: The charging of an object without direct contact from another object.

28. Transfer of Charge Induction
Example of induction: A negatively charged rod is moved close to a metal sphere of neutral charge that is attached to Earth. The negative rod will repel the electrons in the sphere.

29. Transfer of Charge Induction
The electrons in the sphere will be repelled by the negatively charged rod and will move to the Earth. The sphere will have uniformly distributed positive charges on its surface.

30. Induction Example

33. Grounding
An object is considered to be grounded if it is attached to the Earth.
Grounded: attaching an object to the Earth to eliminate excess charge.

35. Coulomb’s Law
F = k q1q2 r2
Where k = 8.99 x 109 N m2 / C2

36. Coulomb’s Law Example Problem
A large harvester ant has accumulated 6 C of charge. A large atta major has accumulated 10 C. The atta is to the left of the harvester. The two ants are separated by 2 cm. What is the force on the atta ant?