What does gradiometer mean?
A gradiometer is an instrument that measures a gradient: the rate at which a physical quantity changes across space. Its best-known application is in geomagnetism, where gradiometers detect small variations in magnetic-field strength between nearby points. Unlike a magnetometer, which ordinarily reports the strength of a field at a particular location, a gradiometer emphasizes the difference between measurements taken at two positions, allowing subtle spatial variations to be detected. Geophysicists may use such instruments on the ground or aboard aircraft to survey geological structures and identify targets such as buried ore. The word is relatively uncommon and technical rather than everyday, but it neatly describes a measurement principle used across several sciences. Its construction also reflects its purpose: “gradient” identifies the changing quantity being examined, while the suffix “-ometer” indicates an instrument.
nounAn instrument for measuring the gradient, or rate of change, of a physical quantity, especially the strength of a magnetic field.
- An instrument that measures the gradient, or spatial rate of change, of a physical quantity, most commonly a magnetic field.
"The geophysical team used an airborne gradiometer to identify variations in the magnetic field beneath the survey area."
"The geophysical team used an airborne gradiometer to map variations in the magnetic field beneath the survey area."
"A sensitive gradiometer placed beside the instrument can reveal whether the magnetic field is becoming more or less uniform."
The standard plural adds -s; plural instruments are commonly described as an array of gradiometers.
"Several gradiometers were positioned across the survey grid."
A gradiometer looks for change between places: the stronger the gradient, the faster the measured field shifts.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does gradiometer come from?
Gradiometer was formed in the 19th century from gradient and the instrument suffix -ometer. Gradient ultimately comes from Latin gradus, meaning “step” or “degree,” a root also preserved in words such as gradation, gradual, and degree. The compound developed as a specialized name for an instrument that detects how a field changes from one position to another.
Related word forms
How gradiometer is actually used
This is a technical noun used chiefly in geomagnetism, geophysics, surveying, and precision measurement. It is more specific than a general gradient-measuring device, since it most often refers to an instrument sensitive to differences in magnetic-field strength between nearby locations.
Easily confused with gradiometer
A gravimeter measures gravitational acceleration or its spatial variations, whereas a gradiometer generally measures how another field, especially a magnetic field, changes across space.