Unit 5 Electromagnetism

1. Unit 5Electromagnetism MAGNETS AND ELECTRICITY

2. Magnetism • When electric charges are stationary, you see an ELECTRIC FIELD • When electric charges are moving, you see a MAGNETIC FIELD • Magnetic forces don’t just act between two magnets • A magnet can also attract certain metals that AREN’T magnets • Examples include nickel, iron, etc. • They are called ferromagnetic metals

6. Oersted’s Principle • Charge moving through a conductor produces a circular magnetic field around the conductor

7. Right-Hand Rule • Grasp the conductor with the thumb of the right hand pointing in the direction of conventional, or positive (+), current flow. The curved fingers point in the direction of the magnetic field around the conductor.

8. Examples • TOP: What is the ‘direction of the current’? • BOTTOM: What is the ‘direction of the magnetic field’?

9. Answers

10. Electromagnetism By using a coiled conductor, you get a stronger magnetic field (B).

11. Right-Hand Rule #2 • Grasp the coiled conductor with the right hand such that curved fingers point in the direction of conventional, or positive (+), current flow. The thumb points in the direction of the magnetic field within the coil. Outside the coil, the thumb represents the north (N) end of the electromagnet produced by the coil.

12. VIDEO • Insert 11 minute magnet video here

14. Example • a) What happens to the strength of the magnetic field around a coil if the current through the conductor is increased from 1.0 A to 2.5 A? • b) What would happen to the field strength if the number of turns in the coil of the electromagnet were reduced by half and the current remained the same?

15. Answers

16. Answers

17. In Summary

18. HOMEWORK • Complete p. 584 (2), and pp. 599 - 601 (20 - 25).