The Cluster's Photoelectric Effect

A page about the photoelectric effect — light ejecting electrons from a metal surface.

The photoelectric effect

The photoelectric effect is the emission of electrons from a metal surface when illuminated by light. The key observations are:

• Electrons are emitted only if the incident light frequency exceeds a threshold nu_0 (the work function nu_0 = phi / h)
• The maximum kinetic energy of emitted electrons is KE_max = h nu - phi, independent of light intensity
• The emission rate is proportional to light intensity, not frequency
• Electrons are emitted instantaneously, with no detectable delay

In the cluster, the edit photoelectric effect is the emission of edit electrons from a edit metal surface when illuminated by edit light.

Einstein's explanation

Einstein explained the photoelectric effect by proposing that light is quantized into photons of energy E = h nu. Each photon can transfer its entire energy to a single electron. The work function phi is the minimum energy to remove an electron from the metal. The photoelectric equation is KE_max = h nu - phi. This explanation won Einstein the 1921 Nobel Prize. In the cluster, the edit Einstein explanation proposes that edit light is quantized into edit photons of edit energy E = h nu.

The work function

The work function phi is the minimum energy to remove an electron from the Fermi level to vacuum. Typical values:

• Cs: 2.14 eV (lowest)
• Na: 2.28 eV
• K: 2.30 eV
• Ca: 2.87 eV
• Cu: 4.65 eV
• Pt: 6.35 eV (highest)

The threshold wavelength is lambda_0 = h c / phi. For Cs: lambda_0 ~ 580 nm (visible). For Pt: lambda_0 ~ 195 nm (UV). In the cluster, the edit work function is the edit minimum energy.

The applications

The photoelectric effect is used in:

• Photomultiplier tubes (PMTs) — single-photon detection
• Photodiodes and photovoltaic cells (solar panels)
• Photographic film (silver halide + light = silver)
• X-ray photoelectron spectroscopy (XPS)
• Night vision devices

In the cluster, the edit photoelectric effect is used in:

• edit PMTs
• edit Photodiodes
• edit Photovoltaic cells
• edit XPS
• edit Night vision devices

This effect

This page is about the photoelectric effect. KE_max = h nu - phi. Threshold: nu > phi/h. Light intensity controls rate, frequency controls energy. Einstein's photon explanation. The effect is real.