1. Electricity & Magnetism
Static, Currents, Circuits
Magnetic Fields & Electro Magnets

2. Atoms… Have neutrons, protons, and electrons.
Protons are positively charged
Electrons are negatively charged

3. Electrons… Are located on the outer edges of atoms…they can be moved.
A concentration of electrons in an atom creates a net negative charge.
If electrons are stripped away, the atom becomes positively charged.

4. - + + + + - - + - + + + - - - + + - - -
The world is filled with electrical charges: Electricity is the energy associated with charged particles - + + + + - - + - + + + - - - + + - - -

5. What is this electrical potential called?
Static Electricity - - - - - + + + - - + +

6. Static Electricity
The build up of an electric charge on the surface of an object.
The charge builds up but does not flow.
Static electricity is potential energy. It does not move. It is stored.

7. Methods of Transfer…
Occurs when there is a loss of static electricity due to three possible things:
Friction - rubbing
Conduction – direct contact
Induction – through an electrical field (not direct contact)

8. Visualizing Lightning
Turn to page 199.
Answer the following questions
When the warm humid air rises to meet the cold air, what causes the air masses to churn together
What electrical property causes the negative charges in the cloud to be attracted to the positive charges in the ground?
Why does the ground below have positive charges?

9. Electricity that moves…
Current: The flow of electrons from one place to another.
Measured in amperes (amps)
Kinetic energy

10. How can we control currents?
With circuits.
Circuit: is a path for the flow of electrons. We use wires.

11. There are 2 types of currents:
Direct Current (DC) – Where electrons flow in the same direction in a wire.

12. There are 2 types of currents:
Alternating Current (AC) – electrons flow in different directions in a wire

13. There are 2 types of circuits:
Series Circuit: the components are lined up along one path. If the circuit is broken, all components turn off.

14. Series Circuit

15. There are 2 types of circuits:
Parallel Circuit – there are several branching paths to the components. If the circuit is broken at any one branch, only the components on that branch will turn off.

16. Parallel Circuit

17. Conductors vs. Insulators
Conductors – material through which electric current flows easily.
Insulators – materials through which electric current cannot move.

18. Examples Conductors: Insulators: Metal Water Styrofoam Rubber Plastic
Paper

19. Activity Identifying Conductors and Insulators
Page 208

20. What is Resistance?
The opposition to the flow of an electric current, producing heat.
The greater the resistance, the less current gets through.
Good conductors have low resistance.
Measured in ohms.

21. What Influences Resistance?
Material of wire – aluminum and copper have low resistance
Thickness – the thicker the wire the lower the resistance
Length – shorter wire has lower resistance
Temperature – lower temperature has lower resistance

22. What is Voltage?
The measure of energy given to the charge flowing in a circuit.
The greater the voltage, the greater the force or “pressure” that drives the charge through the circuit.

23. Difference b/t Volts and Amps
Example – you could say that…
Amps measure how much water comes out of a hose.
Volts measure how hard the water comes out of a hose.

24. Resistance = Voltage / Current
Ohm’s Law
Resistance = Voltage / Current
Ohms = Volts / Amps

25. What is an electromagnet?
Electromagnet – a magnet made from a current bearing coil of wire wrapped around an iron or steel core.

26. What is a generator?
Generator – a machine that changes mechanical energy to electrical energy
Usually use moving magnets to create currents in coils of wire.

27. What is a motor?
Motor – a device that changes electrical energy to mechanical energy that can do work.

28. Creating Electromagnets Lab

29. Practice with Ohm’s Law
Volts
Amps 4
100 25 15
150 10 2 30 9 45 5 6 48 8