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Name: Julia
Status: educator
Grade: 4-5
Location: WI
Country: N/A
Date: 10/31/2005


Question:
If static electricity (i.e. a wool-rubbed balloon making your hair stick up) attracts objects due to the negative charge being built up, then why won't the negative pole of a magnet attract the same objects?


Replies:
Dear Julia,

Magnets do not attract (or repel) stationary charges since the magnetic force is quite different from the electric force, although it is closely related.

Stationary charges are not affected by magnetic fields. Moving charges passing through a magnetic field do feel a force, but the force is perpendicular to the magnetic field line. This is unlike the electric force, which is parallel to the electric field lines. Since electric field lines radiate from electric charges, the electric force will attract charges toward (or away from) the charge producing the electric field.

Since magnetic field lines radiate from the poles of a magnet and the magnetic force is perpendicular to the field lines (as well as perpendicular to the velocity of the charge), a charge passing in front of a pole will have its direction changed, but will not be attracted to or repelled from the pole.

Best, Dick Plano, Professor of Physics emeritus, Rutgers University


Julia,

North and South poles of a magnet are not in any way electric. They are not positive and negative charges of any sort.

Every atom is a tiny magnet. If you attach a coil of wire to a battery so that electric current runs through the coil, the coil becomes magnetic (i.e. an electromagnet). In the same way, the motion and spin of the particles inside an atom cause the atom to be magnetized.

In a standard magnet, many of the atoms "face the same direction". Their tiny magnetic fields work together to produce a large magnetic field. Neither pole of a magnet is positive or negative. The poles just tell you which way the atoms face.

Dr. Ken Mellendorf
Physics Instructor
Illinois Central College



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