Electricity & Magnetism

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

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. What is an electric current? A flow of electrical charges

5. The world is filled with electrical charges: + - + + + - + - - + + + - - - + + - - -

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

7. 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.

8. Static Discharge… • 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)

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. Important FactElectric current will only flow through a complete circuit.

12. Did you Know? When a bulb burns out, a wire inside of it breaks in two. This causes the circuit to no longer have a complete path. It is now an open circuit and electric current cannot flow through it.

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

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

15. http://www.youtube.com/watch?v=HqMqdFNWX4s#t=237

16. 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.

17. What is a series circuit? • All electrical charges flow in the same direction • The parts are connected in one loop • Electric current moves along one path • current goes from power source to load then to another load and finally returns to power source [through wires] • All of the parts are connected one after another

18. Series Circuit

19. http://www.youtube.com/watch?v=u-7k8wpl_ZU&list=PLAO5cUCypo9w-cFeJc2QGqVW0n4ZV42Q1http://www.youtube.com/watch?v=u-7k8wpl_ZU&list=PLAO5cUCypo9w-cFeJc2QGqVW0n4ZV42Q1

20. What is a parallel circuit? • All electrical charges flow through more than one path. These different paths are referred to as branches. • Some of the electric current flows through one branch and some flows through another branch

21. 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.

22. Parallel Circuit

23. http://www.youtube.com/watch?v=MxH7hnuBfC4&list=PLAO5cUCypo9w-cFeJc2QGqVW0n4ZV42Q1http://www.youtube.com/watch?v=MxH7hnuBfC4&list=PLAO5cUCypo9w-cFeJc2QGqVW0n4ZV42Q1

24. Did you know? You can have a combination of a series and parallel circuit. Many circuits in electrical devices, even circuits in your home, are combination circuits!

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

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

29. 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.

30. 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

31. What is a short circuit? A path with almost no resistance It can stop the rest of the circuit from operating properly. Can be dangerous! The wire heats up and may cause a fire.

32. 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.

33. 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.

34. Questions to Ponder... • If you add bulbs to a series circuit, the circuit has higher resistance. What happens to the electric current in the circuit? • If you decrease the resistance of a circuit, what will happen to current in the circuit?

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

36. Practice with Ohm’s Law

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

38. http://www.youtube.com/watch?v=iSuSWi7YThA

39. 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.

40. http://www.youtube.com/watch?v=NqdOyxJZj0U#aid=P89ox56462A

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

42. That’s It !!!!