PHYS208 PHYS208 3/25 Class

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Introduction to Magnetic Fields

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Similarities and Differences of B Compared to E

Magnetic Field Lines

DEMONSTRATION: Field Lines of Bar Magnets

Comparison of Electric and Magnetic Field Lines

The Electric Dipole   The Bar Magnet
Electric Field Lines of Electric Dipole   Magnetic Field Lines of Bar Magnet
+ charge: source of electric field lines
- charge: sink of electric field lines
  Magnetic field lines cannot stop or start,
but must close on themselves.
Notice the similarity in field line structure between the bar magnet and electric dipoles.
However there is one important difference: There are no magnetic monopoles observed!
At this point in the course we have now uncovered the first two of Maxwell's equations.
Gauss's Law:   For Magnetism:
Gauss's Law for the Electric Field   Gauss's Law for the Magnetic Field

Magnetic Force on Moving Charge

DEMONSTRATION: Deflection of Electron Beam in CRT with Magnetic Field

Magnetic force on a moving charge

Discussion of right-hand rule for finding direction of cross product.

Concept Check

Magnetic Force on Infinitesimal Current Segment

Magnetic force on a current segment

Minute Paper

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Last updated April 7, 1998.
Copyright George Watson, Univ. of Delaware, 1997.