Which statement correctly lists the available photocell configurations?

• A. Transmitted beam, retro-reflective, and diffuse sensing
• B. Magnetic, optical, and capacitive
• C. Analog, digital, and hybrid
• D. Infrared, visible, and ultraviolet

Answer: (A)

Photocell configurations describe how a photoelectric sensor is arranged to detect a target. In a transmitted beam setup, the emitter and receiver are separate and aligned so the detector sees the beam until something interrupts it. In retro-reflective configuration, the sensor and a reflector are used together; the beam travels to the reflector and back, and detection occurs when the beam is interrupted or reflected by the object. In diffuse sensing, the target itself reflects light back to the receiver, so no reflector is needed. These three—transmitted beam, retro-reflective, and diffuse sensing—are the standard photocell configurations used in many sensing applications. Other terms describe either sensing principles (magnetic, optical, capacitive) or output formats (analog, digital, hybrid) or light wavelengths (infrared, visible, ultraviolet), which are not the configurations of a photocell.