A device that measures the amount and direction of residual magnetism in a rock sample.

A device that measures the amount and direction of residual magnetism in a rock sample.

• A. Magnetometer
• B. Seismometer
• C. Tachometer
• D. Compass

Answer: (A)

Measuring magnetic properties of rocks to study remanent magnetization is the key idea. A magnetometer detects the magnetic field produced by a rock’s residual magnetism, giving both how strong the magnetization is and which direction the field points. This lets scientists quantify and orient the remanent magnetization left from past Earth magnetic fields, which is essential in paleomagnetism studies. The other instruments don’t fit this purpose. A seismometer records ground vibrations from earthquakes, not magnetic properties. A tachometer measures rotational speed, not magnetism. A compass shows the direction of the local Earth field but doesn’t quantify the amount of magnetization in a rock sample or its precise direction within the rock.

Measuring magnetic properties of rocks to study remanent magnetization is the key idea. A magnetometer detects the magnetic field produced by a rock’s residual magnetism, giving both how strong the magnetization is and which direction the field points. This lets scientists quantify and orient the remanent magnetization left from past Earth magnetic fields, which is essential in paleomagnetism studies.

The other instruments don’t fit this purpose. A seismometer records ground vibrations from earthquakes, not magnetic properties. A tachometer measures rotational speed, not magnetism. A compass shows the direction of the local Earth field but doesn’t quantify the amount of magnetization in a rock sample or its precise direction within the rock.