Which component contains the electronics to detect the presence of an object?

• A. Transducer
• B. Sensor
• C. Controller
• D. Actuator

Answer: (B)

Detecting whether something is present relies on a device that senses a physical condition and turns it into an electrical signal. The sensor is that component: it contains the sensing element and the signal-conditioning electronics needed to produce a usable output when an object is detected. The controller would read that signal to decide what to do, while the actuator would carry out a physical action in response. A transducer converts energy from one form to another, which may be part of a sensing setup, but the element that directly detects presence and provides the signal is the sensor.