Magnetic Materials

posted on 3 Mar 2013 by guy
last changed 1 Aug 2016

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ages: 5 to 12 yrs
budget: $0.00 to $1.00
prep time: 0 to 15 min
class time: 5 to 20 min

This lesson is a brief guide to exploring magnetic materials. It lists a variety of everyday metals, their magnetic properties, and where to find them. Students are encouraged to locate as many examples as they can, and test them with magnets. A checklist for students is attached.

For other ideas and more in-depth explorations of magnetism, check out our curriculum summaries of lessons on Magnets and Materials and Magnets and Motors.

required equipment: magnet
subjects: Physics
keywords: magnetism, material, ferromagnetism, metal

file attachment(s): 


Only a few materials, called "ferromagnetic" materials, exhibit magnetic properties of significant strength. These materials include nickel, iron, cobalt, a few rare earth elements, and some of their alloys. These materials can become magnetized when exposed to an external magnetic field, and consequently attracted to a magnet. In this case, magnetic domains within the material become temporarily aligned to create a magnetic field of their own. Some of these materials may remain in their aligned state even when the external field is removed, thereby making a permanent magnet. See our lesson on Iron and Magnets for more discussion about the microscopic process of magnetization.

Table 1 shows a list of some common metals, their magnetic properties, and where they might be found. A good exercise for students is to try to identify all the magnetic and non-magnetic metals in the area using a magnet. Have them try to identify each metal they come across. One student can act as scribe to keep track of the discoveries on the blackboard, or each student can fill out their own checklist of common metals (attached). More advanced students may try to measure the strength of the magnetic force by recording the distance at which it just cancels the weight of the magnet (i.e. the distance at which the magnet just lifts off the table).

Table 1: Some common metals and their magnetic properties.
metalmagnetic propertiescompositionnotesitems
aluminumnot magneticelement foil, gutter nails, window frames, house siding, aircraft
brassnot magneticalloy of copper and zinclow metal-on-metal friction; good for moving partscandlesticks, doorknobs, zippers, locks, gears, knuckles, musical instruments
bronzenot magneticalloy of copper and (usually) tinan entire age named after itcabinet pulls, doorknobs, cannon barrels, sculpture, weatherstripping, musical instruments, medals, Knuts
chromiumnot magneticelementchromium oxide protects against oxidationplating on steel, lead chromate yellow paint on school buses
cobaltferromagneticelement rechargeable batteries, cobalt aluminate (CoAl2O4) pigment known as cobalt blue, Alnico and Samarium-Cobalt magnets
coppernot magneticelement pipe, wire, cooking utensils, roofing, coinage (not so much in U.S. pennies though, only 2.5%)
goldnot magneticelement jewelry, Dutch guilders, Spanish doubloons, old dental fillings, coatings on electrical connections
hematiteferromagneticiron(III) oxide (Fe2O3)found on Marsjewelry, decorative sculpture
iron, softferromagneticelement horseshoes, old nails, cast iron skillets, meteors
leadnot magneticelement fishing weights, weights on car wheel rims, old paint, old gasoline, lead-acid batteries in cars, framing for stained glass, flashing on buildings
nickelferromagneticelement Canadian nickels before 1982, ingredient in nickel steel, nickel plated fixtures, (not much in U.S. nickel coins, which are 75% copper)
pewternot magneticalloy of tin with copper, antimony, bismuth and sometimes silver old dishes, spoons, candlesticks, whale oil lamps, tea sets
silvernot magneticelement jewelry, silverware, photographic chemicals, coatings on high-end mirrors, coinage
steel, carbonferromagneticalloy of iron and carbon (0.1 to 2.0%)known for taking a sharp edgeknives, scissors, swords
steel, stainlessvariablealloy of iron and chromium (10.5 to about 30%)forms chromium oxide film to prevent rustscrews, tableware, furniture, architecture, automobiles, aircraft
tinnot magneticelement coating on food cans, ingredient in solder
zincnot magneticelement coating on galvanized steel, anode material for batteries, dietary supplement, coinage

 

further resources

brainiac75 at YouTube has posted a video testing the magnetic properties of a wide range of elemental metals. Consider this an experimentally-verified, authoritative source.


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