The emitter in a photo interrupter switch that produces the infrared beam is best described as a ______.

The emitter in a photo interrupter switch that produces the infrared beam is best described as a ______.

• A. Diode
• B. Transistor
• C. Resistor
• D. Capacitor

Answer: (A)

The emitter in a photo interrupter is a light source built as a diode. In these sensors, the emitter is an infrared light-emitting diode (IR LED) that forward-biased emits photons when current flows. A diode is a PN-junction device that conducts mainly in one direction, and LEDs are diodes designed to emit light (in this case, infrared). The other options don’t describe a light-emitting source: a transistor handles switching or amplification, a resistor is a passive current-lensing element, and a capacitor stores charge. So the emitter is best described as a diode because it functions as a light-emitting diode that supplies the IR beam.

The emitter in a photo interrupter is a light source built as a diode. In these sensors, the emitter is an infrared light-emitting diode (IR LED) that forward-biased emits photons when current flows. A diode is a PN-junction device that conducts mainly in one direction, and LEDs are diodes designed to emit light (in this case, infrared). The other options don’t describe a light-emitting source: a transistor handles switching or amplification, a resistor is a passive current-lensing element, and a capacitor stores charge. So the emitter is best described as a diode because it functions as a light-emitting diode that supplies the IR beam.