University:
Kentucky State University
Course:
PHY 212 | General Physics II
Academic year:

2020
Views:

240

Pages:

4
Author:

pravitate8aj11

Magnetism Recall: like electric charges repel, opposite charges attract Analogously: like magnetic poles repel, opposites attract (north and south) Example: bar magnets: S N N S Repel N S N S N Repel Attract S S N N S Attract N S Radical contrast: • isolated + or – electric charges exist (electric monopole) • isolated N and S poles (magnetic monopole) are not observed - + S • every magnet has BOTH a N and a S pole • basic magnetic structure is a dipole SS N SN N N Magnetic Fields • magnetic dipoles create magnetic fields • magnetic field lines point away from north and towards south S N • symbol for magnetic field: B • SI unit for magnetic field: T (Tesla) 1 kg 1 T= Cs These units come from the magnetic force equation, which appears two slides from now. Old unit, still sometimes used: 1 Gauss = 10-4 Tesla. The earth’s magnetic field has a magnitude of roughly 0.5 G. Superconducting magnets can produce a field of over 10 T. Never get near an operating superconducting magnet while wearing a watch or belt buckle with iron in it! Two questions need two chapters to address! 1) How can one create magnetic fields in the first place? (This is the theme of the next chapter: Ampere’s law & Biot-Savart law.) This chapter (28) is not included in the final exam! 2) What are the effects of magnetic fields in the second place? (This is the theme of this chapter) Although cause precedes effect, we will start with the second question!