Verified answer

Well, photocells produce energy by the photoelectric effect.

The photoelectric effect is when particles of light (photons) strike the surface of a metal (photocell) and an electron from the metal is ejected. The energy of the photon is transferred to the kinetic energy of the escaping electron, and some of it goes into removing the electron (this is called the work function of a metal).

The basic formula for this effect is:

E = KE +Φ

E is the energy of the incident photon. KE is the kinetic energy gained by the electron. Φ is the work function, or the minimum energy needed to generate electrons.

Anyways, the escaped electron generates an electric current in a photocell. A very useful application of the photoelectric effect is the solar-powered calculators. Light strikes the surface of that "strip of red brown thingy", which is a photocell, and electrons are given off, generating a current.