1. ELECTRICITY

2. Electricity
The Greeks discovered certain objects such as rods of amber could be rubbed with cat's fur and attract light objects like feathers.
The Greeks used “Electric Force” to describe mysterious forces of attraction and repulsion when amber was rubbed on a piece of cloth. They didn’t understand it nor could they explain it. We know little more about it today.
Neg charged electrons, pos charged protons and neutrons are neutral.

3. Electricity Fundamentals
Atoms are neutrally charged
The nucleus is composed of protons and neutrons.
Neutrons have no charge
Protons are positively charged
Electrons in the orbitals are negatively charged

4. Electricity
Some electrons, particularly in metals are loosely bound and can detach and become “free electrons”
Free electrons as the name implies can move freely from atom to atom
When a force or pressure is applied free electrons begin to move

5. Electricity
The materials that allow the free movement of electrons are called CONDUCTORS
The following metals are considered as the best conductors:
Gold
Silver
Copper
Aluminum

6. Electricity Non Conductors or Insulators: Semi-Conductors: Dry Wood
Glass
Rubber
Mica
Asbestos
Semi-Conductors:
Silicon
Semi-Conductors act a conductors in some circumstances and as insulators in others

7. Electricity For Charged Bodies Unlike charges attract
Like charges repel
Based on what was just stated you might wonder why electrons don’t collapse in on the nucleus. They don’t because the centrifugal force associated with their orbit cancels out their attraction to the nucleus. Demonstration of the wad of paper page 15

8. Electricity
Electrical energy is transferred through conductors by means of movement of free electrons
A material’s ability to conduct current flow determines whether it is a good or bad conductor
Actually current flow moves quite slowly, more slowly than the minute hands on a clock

9. Electricity
The force that moves electrons in a conductor can be called
Voltage
Electromotive Force
Potential Difference

10. Static Electricity
When an atom loses or gains electrons, it becomes positively or negatively charged, respectively.
When a material becomes charged it will keep its positive or negative charge as long as it stays isolated from other materials (Static Charge)
Once it comes in contact with another material the negative charge will flow to the positive.
Should positively charged atoms come into contact with negatively charged atoms the negative charge will jump to the positive.
The rubber sole example
Electrons are much lighter than protons and protons are more or less attached to the nucleus so that is why electrons move to positive rather than the other way around

11. CIRCUITS
In any electric circuit where electrons move around, three things are present:
Voltage
Current
Resistance

12. VOLTAGE ( V or E) Six Methods of Producing Voltage
Friction – Static electricity
Pressure – Compression of crystals
Heating – In copper electrons move away from the heat. In iron they move to the heat.
Light – Photoelectric cells
Chemical Action - Batteries
Magnetism
Pressure – crystals are squeezed to produce voltage
Heating – Voltage can be produced by heating the joint where two unlike metals come in contact
Light – Voltage is produced when light strike photosensitive substances
Magnetism – voltage is produced in a conductor when it is moved through a magnetic field

13. CURRENT (I) Charges are measured in terms of Coulombs (C)
One electron has a charge of x C
1 Coulomb = 6.28 x 1018 electrons
6,280,000,000,000,000,000 electrons
Ampere = 1 coulomb of charge flowing per second
= basic unit of current
= A

14. RESISTANCE (R)
Measure of the opposition of the material to the flow of electrons.
Insulators have high resistance; conductors have low resistance.
Measured in terms of ohms (Ώ)

15. OHM’S LAW
Ohms Law – The current in a circuit is directly proportional to the applied voltage and indirectly proportional to the circuits resistance.
I = current measured in amperes (amps)
E = Voltage
R = Resistance in Ohms

16. OHM’S LAW APPLICATION Battery = 3 volts Resistance = 1.5 ohms
Amperes = ?
Amperes = 2

17. OHM’S LAW TRIANGLE
Another way of writing ohms law:

18. ELECTRIC POWER - WATTS
Watts is the name given to electrical flow – but what flows?
Energy
Energy is measures in joules
A joule of electrical energy can move from place to place along the wires.
The amount of energy that flows in one second is one watt.

19. ELECTRIC POWER - WATTS
Power pertains to the rate at which work is being done.
Work is done whenever a force causes motion
i.e. when voltage causes electrons to move in a circuit work is done
The rate at which this work is done is called the electric power rate and is measured in WATTS

20. ELECTRIC POWER - WATTS
Watts = the amount of voltage across a circuit x the current through the circuit or
Watts = Amperes x Volts
P= I E

21. ELECTRIC POWER - WATTS P = Power in watts I = current in Amperes
R = resistance in ohms