Valosähköisten

Valosähköisten refers to a phenomenon and its related technologies, stemming from the Greek words "phos" (light) and "ēlektron" (amber, from which electricity was first derived). In its most fundamental sense, it describes the emission of electrons from a material when light shines on it. This effect is directly dependent on the frequency of the incident light, not its intensity, a key observation that led to the development of quantum theory. The energy of the photons in the light must exceed a certain threshold, known as the work function, for electrons to be liberated.

The practical applications of valosähköisten are widespread. The most common example is the photovoltaic effect, which is the basis for solar cells. These devices convert sunlight directly into electricity using semiconductor materials. Other applications include light sensors, photomultipliers, and image sensors found in digital cameras. The discovery of the valosähköisten effect by Heinrich Hertz and its subsequent explanation by Albert Einstein earned him the Nobel Prize in Physics in 1921. The understanding and manipulation of this phenomenon have been crucial in the advancement of electronics and renewable energy technologies.