What can an LED be used for?

An LED, or Light Emitting Diode, is commonly used as a fiber optic signal source due to its ability to emit light efficiently when an electric current passes through it. This emitted light can be coupled directly into optical fibers to transmit data over long distances with minimal loss, making LEDs highly suitable for applications in telecommunications and data networks.

The use of LEDs in this capacity leverages their quick response time and the ability to modulate light intensity, which is essential for encoding information in optical communication. This capability is particularly beneficial in environments where high-speed data transmission is required.

In contrast, the other options have characteristics that do not align with the functionalities of an LED. Power sources typically refer to batteries or power supply units, while microcontrollers are integrated circuits designed to process instructions, and capacitors store electrical charge. None of these roles match the intrinsic properties of an LED.