What phenomenon does selenium exhibit when exposed to light?

When selenium is exposed to light, it exhibits increased conductivity. This phenomenon is related to the way selenium responds to photons; when light hits the selenium material, it energizes its electrons, allowing them to move more freely. This increase in electron mobility results in a higher conductivity of the material.

This property of selenium is utilized in various applications, particularly in photoelectric cells and light sensors, where the change in conductivity due to light exposure is the key mechanism for their operation.

In contrast, increased voltage and reduced resistance do not specifically correlate with selenium’s behavior under light exposure. Increased capacitance is also not applicable here, as capacitance relates to a material’s ability to store electrical energy in an electric field, which is not influenced by light in the same way that conductivity is.