1. The materials are electrically charged.
Electrostatics
Why does rubbing a balloon on your hair make your hair stand up?
Why does sliding with sock feet on a carpet create a “shock” when you touch someone else?
The materials are electrically charged.

2. Electrostatics Electrostatics is the study of electricity at rest.
Electrostatics involves electric charges, the forces between them, and their behavior.
Atoms are the fundamental unit of matter and they are held together with positive and negative particles. Electrical forces are very strong and, because there are positive and negative charges, overall they balance each other out.

3. Electrostatics There are two types of electric charges:
Like charges repel
Unlike charges attract
Type of charge
Symbol C
Positive charge +q
+1.60 x C
Negative charge -q
-1.60 x C

4. Electrostatics Remember from chemistry:
The nucleus of the atom is positive and it is surrounded by negatively charged electrons
Electrons are identical (same amount of charge and same mass)
Atoms usually have the same number of protons and electrons, so the atom has a net charge of zero

5. Electrostatics
There are a lot of atoms in your hair and on a balloon. When you rub a balloon on your hair, the hair has +q and the balloon has –q. This means that your hair is giving electrons to the balloon.
Charge has a tendency to be transferred between unlike materials.
Rubbing the objects together increases area of contact and helps enhance the charge transfer process.
Electric charge is always conserved!

6. Electrostatics Millikan Oil Drop Experiment – YouTube
Millikan found that when an object is charged, its charge is always a multiple of some fundamental unit of charge.
He found that the fundamental unit of charge for an electron is: x C

7. Electrostatics
In metals, transfer of charge can occur over a small region because the charge distributes itself over the entire surface of a metal.
Metals are electrical conductors = a material in which charges can move freely.
Plastic, rubber, glass, silk are electrical insulators = materials in which charges cannot move freely.

8. Electrostatics Two ways to charge objects:
By contact – when rubbed together
By induction – by bringing a charged object near another charged object and grounding the conductor.
Grounding = being connected through the Earth.

9. Charging by induction – by grounding, the electrons are drained off and the resulting charge is completely positive.