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DC Theory 27
Understanding the principles of magnetism
| Question | Answer |
|---|---|
| 1. Since electrons are charged particles they will have a ___ field around them | eletrostatic |
| 2. The combination of electrostatic and magnetic fields creates a ___ | electromagnetic field |
| 3. The magnetic lines around a spinning electron are ___ to the electrostatic lines | perpendicular ????p 184 185 |
| Draw the fields below: Electrostatic, Magnetic, combined Electromagnetic | p 185 |
| 4. describe the "electron spin" theory of magnetism | p 185 |
| 5. When magnetic domains are developed, they will react like small___ | permanent magnets |
| 6. What are the three laws of magnetism | 1) energy is needed to create a magnet but not to maintain it 2) like poles repel; unlike poles attract 3) magnetic force between poles is proportional to the pole strength and inversely proportional to the square of the distance between them |
| 7. The attraction or repulsion that occurs when magnets are held close to each other is caused by the ___ that flow into and out of a magnet | magnetic lines of force |
| 8. The flux lines of a magnet leave the ___ end and enter the ___ end | North, South |
| 9. When like poles face each other, the magnets ___ each other because the lines of flux are moving in ___ directions but when opposite poles face each other ___ each other because the lines of flux are moving in the __ direction | repel, opposite, attract, same |
| 10. The ability of a material to focus lines of flux is called ___ | permeability |
| 11. Opposition to the passage of flux lines is called ___ | reluctance |
| 12. Flux lines run___ to each other, but will never ___ | parallel, cross |
| 13. List the six rules for magnetic lines of flux | 1) flux lines are continuous and form closed loops 2) the lines never cross 3) lines in same direction repel and stregnthen magnet; lines in opp direction attract and weaken magnet 4) lines try to contract pulling unlike poles together |
| continue | 5) magnetic lines of force pass through nearly all material 6) lines enter an leave the pole at right angles and travel north to south around the magnet |
| 14. Flux lines are ___ (less/more) dense at poles, and the magnetic field is ___ ( weaker/stronger) | more, stronger |
| 15. Nickel, cobalt, and iron are called ___ materials because they are easily magnetized | ferromagnetic |
| 16. List 5 examples of paramagnetic materials that can be magnetized, but not as easily as ferromagnetic materials | aluminum, copper, chromium, platinum, titanium |
| 17. Graphite is an example of a ___ material | diamagnetic |
| 18. A magnet can be demagnetized by __ it, __ , or exposing it to a magnetic field caused by a ___ | striking, heating, alternating current |
| 19. Flux lines will pass through any material, but they will take the path of least ___. This allows us to __ devices that are adversely affected by magnetic fields. | reluctance, sheild |
| 20. Like poles of a magnet __ , whereas unlike poles __ | repel, attract |
| 21. Draw the force fields on page 271 workbook | |
| 22. A material that retains its magnetic properties is called a____ magnet, and one that loses this characteristic easily when its magnetized force is removed is called a ___ magnet | permanent, temporary |
| 23. A magnet has two poles. They are the ___ pole and he ___ pole. | North, South |
| 24. How is the north pole of a magnet designated | If the magnet is free to move it will point north |
| 25. Permanent magnets are made of ___ and temporary magnets are made of ___ | steel, soft iron |
Created by:
JoshHampton