Photoelectric Effect
First, explore the phenomenon. Then use the observations from the simulation to understand the chemistry behind photoelectric emission.
What is the photoelectric effect?
The photoelectric effect is the phenomenon in which electrons are emitted from a metal surface when electromagnetic radiation of suitable frequency falls on it. The emitted electrons are called photoelectrons.
The effect depends on the frequency of the incident radiation and on the nature of the metal. For a given metal, photoemission does not occur when the frequency of the incident radiation is below a certain minimum value called the threshold frequency.
Four observations from the simulation
1. Frequency
Increasing the frequency increases the energy of each photon. If the frequency is below the threshold frequency, electrons are not emitted.
2. Intensity
At a fixed frequency, changing intensity changes the number of photons incident on the surface. It does not change the energy of an individual photon.
3. Metal
Different metals have different work functions. Therefore, the frequency required for photoemission is different for different metals.
4. Stopping potential
The emitted electrons have a maximum kinetic energy. The stopping potential is related to this maximum kinetic energy.
The key idea
According to the photon picture, radiation consists of photons. The energy of a photon is proportional to its frequency. A part of this energy is used to overcome the work function of the metal and the remaining energy appears as the maximum kinetic energy of the emitted electron.