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Optoelectronic Devices
10 questions By Tony R. Kuphaldt
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Question 10 of 10
Photodiodes, phototransistors, and light-emitting diodes all play important roles in optical communications networks, where digital (on/off) signals are communicated over long distances as pulses of light energy rather than voltage or current.
Why are LEDs greatly preferred over other electro-optical devices such as incandescent lamps or gas-discharge bulbs? What can an LED do that a small electric lamp cannot?
Reveal answerSemiconductor-based light emitting devices are capable of turning on and off much, much faster than incandescent or gas-discharge devices.
Notes:In digital communications networks, speed is an essential quality. Ask your students why this is so, and by association, why semiconductor-based light sources are almost exclusively used in optical networks.
