Which sensor type is not listed among the short-range sensors (hall effect, inductive, capacitive)?

Which sensor type is not listed among the short-range sensors (hall effect, inductive, capacitive)?

• A. Ultrasonic
• B. Hall effect
• C. Inductive
• D. Capacitive

Answer: (A)

Proximity sensing at short range relies on detecting a nearby object's presence by changes in an electromagnetic field or capacitance. The common short-range sensor types use magnetic or electric fields: inductive sensors detect metal by changes in coil inductance, capacitive sensors sense shifts in capacitance caused by nearby dielectric materials, and Hall effect sensors respond to magnetic fields. Ultrasonic, on the other hand, measures distance by emitting sound waves and timing their return after reflection, which is a different sensing approach and typically covers longer ranges. Because ultrasonic relies on acoustic time-of-flight rather than field or dielectric changes, it is not listed among the short-range sensor types.

Proximity sensing at short range relies on detecting a nearby object's presence by changes in an electromagnetic field or capacitance. The common short-range sensor types use magnetic or electric fields: inductive sensors detect metal by changes in coil inductance, capacitive sensors sense shifts in capacitance caused by nearby dielectric materials, and Hall effect sensors respond to magnetic fields. Ultrasonic, on the other hand, measures distance by emitting sound waves and timing their return after reflection, which is a different sensing approach and typically covers longer ranges. Because ultrasonic relies on acoustic time-of-flight rather than field or dielectric changes, it is not listed among the short-range sensor types.