Which unit is used to measure the Earth's magnetic field strength?

Which unit is used to measure the Earth's magnetic field strength?

• A. Tesla
• B. Oersted
• C. A/m
• D. Gauss

Answer: (D)

Magnetic-field measurements distinguish between magnetic flux density (B) and magnetic field intensity (H). For Earth’s field, the quantity of interest is the magnetic flux density, and the conventional way to express this in geophysics is in Gauss, a CGS unit. The Earth’s surface field is on the order of a few tenths of a Gauss (roughly 0.25–0.65 G), which corresponds to about 25–65 microteslas in SI units. Because Gauss is the traditional unit used in many geomagnetic references, it’s the unit most often associated with measuring Earth’s magnetic field strength. In contrast, Tesla is the SI unit for B (1 T = 10,000 G), and the other two options refer to magnetic field strength H rather than flux density B.

Magnetic-field measurements distinguish between magnetic flux density (B) and magnetic field intensity (H). For Earth’s field, the quantity of interest is the magnetic flux density, and the conventional way to express this in geophysics is in Gauss, a CGS unit. The Earth’s surface field is on the order of a few tenths of a Gauss (roughly 0.25–0.65 G), which corresponds to about 25–65 microteslas in SI units. Because Gauss is the traditional unit used in many geomagnetic references, it’s the unit most often associated with measuring Earth’s magnetic field strength. In contrast, Tesla is the SI unit for B (1 T = 10,000 G), and the other two options refer to magnetic field strength H rather than flux density B.