IB Physics

​Quantum Physics - Photoelectric Effect

Electrons are bound to metal

Absorption of a photon (energy) allows the electrons to break free and be launched away from the metal surface​

Basic premise of the Photoelectric effect

​Photoelectric effect

Different electrons are attracted to the metal ions with different energies,

The outermost electrons are attracted the least

Such attraction energy is called the "workfunction" of the metal​

The quantifiable electron​

The outermost electron

The Outermost electron will be launched with the greatest KE, denoted as KEmax. This is a fixed value.

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Referring to conservation laws, we can derive the Einstein equation

​

​ hf = ϕ + E_k

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The fastest electron

Einstein equation

​

​ hf = ϕ + E_k

​​

Incoming light energy is used to overcome the electron's attraction to the metal atom, and excess energy is imparted to the electron as kinetic energy

Conservation of Energy

Einstein equation

​

​ hf = ϕ + E_k

​​

Incoming light energy is used to overcome the electron's attraction to the metal atom, and excess energy is imparted to the electron as kinetic energy

Conservation of Energy