Proximity switches usually sense the presence or absence of a target by means of physical contact.

• A. True
• B. False
• C. They sense by light
• D. They sense by pressure

Answer: (B)

Proximity sensing is non-contact. Proximity switches detect a target without touching it, using ways like electromagnetic fields (inductive), changes in capacitance (capacitive), light energy (optical/IR), or sound waves (ultrasonic). Because the sensing relies on interaction with energy fields or light rather than physical contact, the statement is not correct. While some proximity sensors may use light, many rely on magnetic fields or capacitance, and all of them aim to detect presence without touching the object. Sensing by pressure would require contact, which is not how proximity switches operate.