1. MAGNETS AND ELECTROMAGNETISM

2. MAGNETISM Electric currents or the movement of electrons in an atom will create the property of magnetism in an object What do we know about magnets right now?

3. What is a Magnet

4. MAGNETS ARE….. A magnet is a material that attracts iron or matter that contains iron. There are some naturally occurring magnets, for example certain types of rock are magnetic Magnets will be attracted to or repelled by another magnet (north/south poles) Magnets will always point North when allowed to swing freely

5. MAGNETIC FIELDS Magnetic fields are the area of force around a magnet Magnetic fields are shown in a diagram with magnetic field lines Magnetic field lines always leave the North Pole and enter the South Pole Magnetic field lines never cross

6. Magnetic Field Diagram

7. MAGNETIC INTERACTIONS North to North North to South South to South

8. Magnetic Interactions:

9. Magnetic Materials: The way that electrons are arranged in the atom will determine how magnetic the material is…. 3 Types of Magnetic Material Diamagnetic Paramagnetic Ferromagnetic

10. Types of Magnetic Material Diamagnetic: – Lead and diamonds are good examples – Produce no magnetic effect – Fields of individual electrons are cancelled leaving the material without a magnetic field

11. Types of Magnetic Material Paramagnetic: – Aluminum is a good example – The individual electrons do not cancel each other out, but the arrangement is random – Random arrangement makes the magnetic force weak

12. Types of Magnetic Material Ferromagnetic: – Small group of metals – Iron, nickel and cobalt are the best examples – Individual atoms are not arranged randomly, but are aligned in magnetic domains – Due to common alignment, the magnetic effect is quite strong

13. Earth’s Magnetism

14. Electromagnetic Forces Electrons are bound to the nucleus by an electromagnetic force The force is the attraction between the negatively charged electrons outside of the nucleus and the positively charged protons inside the nucleus The electrons have momentum orbiting the nucleus, therefore they do not crash into the nucleus.

15. Electric Current and Magnetism Whenever there is electricity there is a magnetic field This can be observed by bringing a compass needle near an electric current or coil Electromagnetism

16. Permanent vs. Electromagnets Permanent magnet is always magnetic Retains properties even when it is not close to other magnets Strength cannot be changed Electromagnets can be turned on and off Produced by the electric current and magnetized core Strength can be hundreds or thousands of times larger than a permanent magnet and can be adjusted

17. Common Electromagnets Video Tapes Computer Hard Drives Credit Cards Junk Yard Cranes Generators

18. ELECTROMAGNETS Created by electric current that travels through wires or coils wrapped around an iron core The core will concentrate and amplify the field

19. ELECTROMAGNETS The strength of an electromagnet can be increased by increasing the number of turns in the coil or wire wrapped around the core. The strength can also be increased by increasing the electric source (add another battery)

20. The Right Hand Rule You are able to tell which end is NORTH by following this rule. If the coils are wrapped in the same direction as your right hand, then the thumb points NORTH

21. Factors that Effect the Electromagnet 1.The amount of current 2.The amount and type of material at the core 3.The number of turns in the coil or wire

22. All magnetism comes from electricity That includes electricity from electrons in the atom