The permeameter is an instrument for rapidly measuring the

electromagnetic In physics, electromagnetism is an interaction that occurs between particles with electric charge via electromagnetic fields. The electromagnetic force is one of the four fundamental forces of nature. It is the dominant force in the interacti ...

permeability of samples of

iron Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's o ...

steel Steel is an alloy of iron and carbon that demonstrates improved mechanical properties compared to the pure form of iron. Due to steel's high Young's modulus, elastic modulus, Yield (engineering), yield strength, Fracture, fracture strength a ...

with sufficient accuracy for many commercial purposes. The name was first applied by

Silvanus P. Thompson Silvanus Phillips Thompson (19 June 1851 – 12 June 1916) was an English professor of physics at the City and Guilds Technical College in Finsbury, England. He was elected to the Royal Society in 1891 and was known for his work as an electr ...

to an apparatus devised by himself in 1890, which indicates the mechanical

force In physics, a force is an influence that can cause an Physical object, object to change its velocity unless counterbalanced by other forces. In mechanics, force makes ideas like 'pushing' or 'pulling' mathematically precise. Because the Magnitu ...

required to detach one end of the sample, arranged as the core of a straight

electromagnet An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. Electromagnets usually consist of wire (likely copper) wound into a electromagnetic coil, coil. A current through the wire creates a magnetic ...

, from an iron

yoke A yoke is a wooden beam used between a pair of oxen or other animals to enable them to pull together on a load when working in pairs, as oxen usually do; some yokes are fitted to individual animals. There are several types of yoke, used in dif ...

of special form; when this force is known, the permeability can be easily calculated.

References

Measuring instruments {{electromagnetism-stub permeameter.aspx www.glossary.oilfield.slb.com/en/Terms/p/permeameter.aspx