1. 16 – 1 Electric charge

2. Structure of the Atom small, dense nucleus
Contains protons and neutrons
surrounded by electron cloud
Protons are + charged
Electrons are – charged
Neutrons are neutral (no charge)

3. Properties of electric charge:
There are 2 kinds of charge; ( + ) and ( - )
Similar charges repel and opposite charges attract

4. Properties of electric charge con’t:
Charge is conserved
Charge can be transferred from one object to another but not created or destroyed

5. Properties of electric charge con’t:
Charge is quantized.
It comes in discreet amounts
Fundamental unit of charge = e
This is the charge on a proton or electron, e = 1.60x C
SI unit of charge is the coulomb,C

6. Millikan Oil-Drop Experiment
Measured the elementary charge, e
Found every charge had an integral multiple of e
qt = n e

7. Atomic Particles Particles Charge ( C) Mass (kg) Electrons Protons
-1.60x10-19
9.109 x 10-31
Protons
+1.60x10-19
l.673x10-27
Neutrons

8. Objects can be classified into categories based on how they transfer charge.
Conductor
Insulator
Semiconductor
Superconductor

9. Conductor
Transfers charge easily, outer electrons are loosely bound to atoms
Ex: metals like gold, silver, copper

10. Insulator
Materials that do not transfer charge easily, outer e- bound tightly to atom
Example: rubber, glass

11. Semiconductor – insulator in pure state, good conductor when small impurity is added
Ex: Silicon, Germanium

12. Superconductor – material becomes a perfect conductor (no resistance) at or below a certain temperature
Ex: Zinc, Aluminum, Tin & Mercury

13. Most materials can be charged by friction but only conductors can be charged by induction

16. Polarization
In most neutral atoms or molecules, the center of positive charge coincides with the center of negative charge.
in presence charged objects, the centers my shift slightly

17. Examples