Photoelectric Effect
Definition and meaning of Photoelectric Effect in chemistry.
The photoelectric effect is the emission of electrons from a material when light of a sufficient frequency shines on its surface.
In more detail
This phenomenon provided early evidence for the particle nature of light, as classical wave theory could not explain why low-frequency light, regardless of its intensity, failed to eject electrons. Albert Einstein proposed that light consists of discrete packets of energy called photons, and an electron is ejected only if a single incident photon transfers enough energy to overcome the material's specific work function. The kinetic energy of the ejected electron is directly proportional to the frequency of the incident light, while the number of electrons emitted depends on the light's intensity.
Key facts
| Field | Physical Chemistry |
|---|---|
| Key Concept | Particle nature of light |
| Formula Example | Zn |
Shining high-frequency ultraviolet light on a zinc plate causes it to emit electrons, whereas shining low-frequency red light on it, even a very bright beam, does not cause any emission.
Frequently asked questions
Does increasing the brightness of light increase the kinetic energy of emitted electrons?
No, increasing brightness only increases the number of electrons emitted, provided the light has a high enough frequency.
Who explained the photoelectric effect?
Albert Einstein explained it in 1905 using the concept of quantized photons.