What type of diode produces light when current flows through it?

The type of diode that produces light when current flows through it is the Light Emitting Diode, commonly known as an LED. LEDs work on the principle of electroluminescence, where electrons recombine with holes within the device, releasing energy in the form of light. The specific wavelengths of light emitted by an LED can vary based on the materials used in its construction, allowing for different colors of light to be produced.

In contrast, while laser diodes also emit light, they do so through a different mechanism involving stimulated emission, which enables them to produce coherent light (laser light). Violet diode is not a commonly recognized type of diode; it may refer to a specific wavelength of an LED but does not stand alone as a recognized class. A semiconductor diode is a broad category that includes various types of diodes, including LEDs but does not specifically denote a diode that emits light.

By understanding these distinctions, it becomes clear that the Light Emitting Diode is specifically designed to convert electrical energy directly into light efficiently, making it the correct answer.