1. ELECTRICITY AND MAGNETISM

2. Electricity

3. Electric charges are from protons which are positive and electrons which are negative . Static Electricity – accumulation of excess electric charges on an object Atoms become charged by gaining or losing electrons. + -

4. opposite charges attract
Law of Conservation of Charge – electric charges can be transferred from object to object, but it cannot be created or destroyed. Positive and negative charges exert forces on each other. + - + -
opposite charges attract
like charges repel

5. CONDUCTORS VS. INSULATORS
Conductors – material in which electrons move easily
Ex. Metals
Insulators – material in which electrons are not able to move easily
Ex. wood, plastics, rubber
Charging Objects
Charging by Contact - process of transferring charge by touching or rubbing
Charging by Induction - rearrangement of electrons on a neutral object caused by nearby charged objects

6. Electric Current

7. Electric Current – net movement of electric charges in a single direction through a wire or conductor.
Voltage Difference – force that causes electric charges to flow; charges flow from high voltage low voltage

8. Circuit – a closed path that electric current follows.
Battery, wires, and voltage difference allows current to flow.

9. BATTERIES
Dry Cell
Chemical reactions occur in a moist paste causing transfer of electrons
Resistance – tendency for a material to oppose the flow of electrons, changing electrical energy into thermal and light energy.
Wet Cell
Contains two connected plates made of different metals in conducting solution.
Ex. Car Battery

10. Voltage diff Current = Resistance
Making wires thinner, longer or hotter increases resistance All materials have some electrical resistance measured in ohms. (Ω) Ohms Law – current in a circuit equals voltage difference divided by resistance.
Voltage diff
Current =
Resistance

11. Electrical Circuits

13. Electrical energy enters your home at the circuit breaker or fuse box and branches out to appliances, wall socket and lights.
Circuit breakers – small piece of metal that bends when it gets hot, opening circuit and stopping current flow.
Electronic fuse - small piece of metal that melts if current becomes to high, opening circuit

14. Magnetism

15. Magnetism – refers to the properties and interactions of magnets in which there is a force of attraction or repulsion between like or unlike poles.
Strength of force between two magnets depends on the distance between them.
Magnetic field – exerts a force on
other magnets and objects made of magnetic materials (strongest closed to magnet)

16. All magnets have a north pole and a south pole.
LIKE POLES REPEL
UNLIKE POLES ATTRACT

17. MAGNETIC MATERIALS Only few metals, such as iron, cobalt, and nickel are attracted to magnets or can be made into permanent magnets. Magnetic domains – group of atoms with aligned magnetic poles (too small to be seen with eye) Permanent magnets are made by placing a magnetic material in a strong magnetic field, forcing magnetic domains to line up.

18. Magnetism And Electricity

19. When electric current flows through a wire, a magnetic field forms around the wire. Strength of magnetic field depends on the amount of current flowing in the wire.
WIRE
ELECTRON FLOW

20. Electromagnets – a temporary magnet made by wrapping a wire coil carrying a current around an iron core.
Increases strength of the magnetic field by adding more turns to wire coil (solenoid) or increasing the current passing through the wire
Electric motor – a device that changes electrical energy into mechanical energy

21. DIRECT AND ALTERNATING CURRENT
In a simple electric motor, an electromagnet rotates between the poles of a permanent magnet.
DIRECT AND ALTERNATING CURRENT
Direct Current (DC) – current that flows in only one direction through a wire
Ex. A battery
Alternating Current (AC) - reverses the direction of the current flow in regular patterns.
Ex. Plugging toaster into Wall outlet