Magnetic sensor

A magnetic sensor detects a magnetic field and converts its presence, direction, or strength into a measurable signal. Sensors use different physical effects to measure fields or changes in them.

Hall effect: A voltage develops across a current-carrying conductor or semiconductor when a magnetic field is applied perpendicular to the current. Hall-effect sensors use this transverse voltage to measure field strength or detect nearby magnets.
Electronic compass: A navigation instrument that estimates heading by measuring Earth's magnetic field electronically. Three-axis magnetic sensors let electronic compasses determine magnetic north.
Magnetometer: An instrument that measures the direction, strength, or variation of a magnetic field. A magnetic sensor is a sensing element; a magnetometer is an instrument built to measure fields.
Magnetic field: A vector field that describes magnetic influence on moving electric charges, currents, and magnetic materials. It is the physical quantity every magnetic sensor responds to.
Sensitivity (electronics): The change in a device's output divided by a change in its input. Sensitivity determines how small a field change a magnetic sensor can resolve.
Magnetoresistance: The electrical resistance of a material changes when it is exposed to a magnetic field. Magnetoresistive sensors infer magnetic fields from changes in resistance.
Wheel speed sensor: A device that measures the rotational speed of a vehicle wheel or axle. Magnetic sensors detect passing teeth or encoded poles to measure wheel rotation.
Magnetic switch: An electrical switch that changes state in response to a magnetic field. A switch reports a threshold crossing, while many magnetic sensors provide continuous measurements.
Magnetic flux density: A vector quantity describing magnetic flux per unit area, commonly measured in teslas. Many sensor specifications express sensitivity and range in terms of magnetic flux density.
Noise (electronics): Unwanted random fluctuations in an electrical signal that obscure information. Noise sets a practical floor on the weakest magnetic field a sensor can detect.

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