Which statement about the three components of a photoelectric sensor is true?

• A. The three are transmitter, receiver, and cables.
• B. The three are transmitter, receiver, and power supply.
• C. The three are transmitter, detector, and contacts.
• D. The three are transmitter, receiver, and contacts.

Answer: (D)

Understanding what a photoelectric sensor is made of helps: it has a light-emitting part that sends a beam, a light-detecting part that receives or monitors that beam, and an output interface that delivers the sensing signal to the rest of the system. The transmitter and receiver handle the sensing itself, while the contacts provide the actual switch output (the NO/NC contacts you wire into a control circuit). The power supply and cables are essential for setup and power, but they are not the three functional components that define the sensing operation and its output. So stating that the three components are transmitter, receiver, and contacts correctly identifies the parts that constitute the sensing action and its signal interface.