Lab 19 – Diamagnetism and Paramagnetism:
Purpose
Students will explore the magnetic
properties of non-ferrous materials.
Theory
Almost all materials have magnetic
properties, but they are so weak that
they were overlooked for centuries. In
atoms, the electrons spin on their own
axes, and the circulation of this charge
creates dipole moments. These are tiny
magnets that can align with any nearby
field, attracting the substance to strong
permanent magnets. This is known as
paramagnetism. The problem is that
electrons normally pair off in atoms so
that every dipole is countered by one in
the opposite orientation, diminishing
the paramagnetic effect so much that
the orbits of the electrons around the
atomic nucleus take precedence. This
kind of dipole actually grows weaker if
it happens to be aligned with exterior
fields, and stronger if it opposes it. As a
result, most substances are repelled by
magnets. This is diamagnetism.
Procedure

1. Fill a wide, shallow, non-metal dish
   with water to within half an inch of full.
2. Find a plastic soda bottle cap and
   set it afloat in the middle of the dish.
   Give the water time to become still, but
   keep the lid away from the edges of the
   dish because it will be very attracted to
   them if it gets too close due to a surface
   tension effect.
3. In the kit, find the set of three diskshaped rare-earth magnets. These are
   brittle, so don’t drop them! If broken,
   the edges can be razor sharp. Carefully
   remove the three plastic spacer rings
   between them to make one powerful
   magnet out of the three.
4. If the lid is sitting still in the center
   of the bowl now, bring the magnet face
   to within a millimeter of the lid. Keep it
   there without touching the lid or the
   water. Touching either means starting
   over by getting everything still again.
5. Watch for the lid to start drifting
   away from the magnets.
6. Find a business-card-sized scrap of
   aluminum foil and shape it into a bowl
   that will float on the water in place of
   the plastic lid. When it is still, repeat
   the magnet test and look for it to be
   attracted instead of repelled.
7. Find any other non-ferrous object
   or material that can be floated on the
   water while sticking up enough for the
   face of the magnet to effect it. Try to
   determine if it is attracted or repelled.
   Figure 19: Holding the magnet by an object
   without touching it or the water is tricky.
   Analysis
   Answer these in Canvas:
8. What third object was chosen?
9. Is it diamagnetic or paramagnetic?