Presentation - 500
Scientist: Robert Ferrell
Email: Robert@Ferrell.com
Science Background: Physics
Presentation Name: Magnetism, Propane Torches and the Higgs Boson
Presentation Subject: Phase changes you can't see
School Districts/Areas Offered: All
Grades Offered: 8th through 12th
Days Offered: Any
Hours Offered: Any
AV or Other Requirements: Computer projector, maybe wifi (not mandatory)
Synopsis:
Everyone is familiar with phase transitions - ice melting, water boiling. But many of the most interesting transitions aren't obviously visible. The transition from (ferro)magnetic to paramagnetic (which is pretty much non-magnetic) can be seen with an experiment, but there's no visible change in the magnetic material.
Iron is only (ferro)magnetic below about 1040K, the Curie Temperature. It's easy to see that by heating up a metal washer stuck to a magnet. Once the washer gets hot enough it will fall off. (Need to use magnets with a higher Curie temperature than iron.)
Other ferromagnetic materials have different Curie temperatures. Tc of Gadolinium is 19 *C, just around room temperature. Students can make a Gd sample stick to a magnet by immersing it in ice water. They can then reheat it with a hair dryer and it will fall off a magnet.
For the right students it's a small conceptual step from the ferromagnetic phase transition to the Higgs field and the source of mass.
Comments: Phase transitions show up everywhere and are an active area of research.
Scientist: Robert Ferrell
Email: Robert@Ferrell.com
Science Background: Physics
Presentation Name: Magnetism, Propane Torches and the Higgs Boson
Presentation Subject: Phase changes you can't see
School Districts/Areas Offered: All
Grades Offered: 8th through 12th
Days Offered: Any
Hours Offered: Any
AV or Other Requirements: Computer projector, maybe wifi (not mandatory)
Synopsis:
Everyone is familiar with phase transitions - ice melting, water boiling. But many of the most interesting transitions aren't obviously visible. The transition from (ferro)magnetic to paramagnetic (which is pretty much non-magnetic) can be seen with an experiment, but there's no visible change in the magnetic material.
Iron is only (ferro)magnetic below about 1040K, the Curie Temperature. It's easy to see that by heating up a metal washer stuck to a magnet. Once the washer gets hot enough it will fall off. (Need to use magnets with a higher Curie temperature than iron.)
Other ferromagnetic materials have different Curie temperatures. Tc of Gadolinium is 19 *C, just around room temperature. Students can make a Gd sample stick to a magnet by immersing it in ice water. They can then reheat it with a hair dryer and it will fall off a magnet.
For the right students it's a small conceptual step from the ferromagnetic phase transition to the Higgs field and the source of mass.
Comments: Phase transitions show up everywhere and are an active area of research.
