How to Measure How Strong a Magnet Is
The strength of a magnetic field is measured in units of mass / (electrical charge x time) and its standard unit of measure is the tesla (T). A tesla is defined as 1 kilogram / coulomb second and a gauss is equal to 0.0001 tesla. There are a variety of devices that measure magnetic fields, depending on the specific strength and type of magnetic field being measured. Scientific magnetometers that measure magnetic fields on Earth are typically extremely sensitive.
Things You'll Need
- Capacitive Cantilever Beam Magnetometer
- Piezoresistive Cantilever Magnetometer
- Vibrating Sample Magnetometer
- Magneto-Optical Kerr Effect Probe
Instructions
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Examine the strength of some common magnets. The magnetic field of the Earth is about a half-gauss and a refrigerator magnet might have 100 gauss. The most powerful permanent magnet is based on neodymium and a small one may exert about 2,000 gauss. A large electromagnet can have a magnetic field of up to 15,000 gauss.
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Measure the force on the moment in a magnetic field with a capacitive cantilever beam magnetometer. These devices have a resolution of about 10^-10 joules per tesla (J/T) in a field of 0.1 T per centimeter.
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Measure the magnetic moment in a very small sample with a piezoresistive cantilever magnetometer. These extremely sensitive magnetometers calculate the magnetic moment by measuring the changes in electrical resistance that occur when the sample is bent.
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Measure larger samples with a vibrating sample magnetometer. This device can measure samples up to 6 millimeters in diameter and has a resolution of 10^-6 J/T. A vibrating sample magnetometer can operate in a field of up to 33 tesla.
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5
Measure magnetism on thin films, liquids and gasses with a magneto-optical Kerr effect probe. This device can function in magnetic fields of up to 20 T on samples that are up to two centimeters in diameter.
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