2024 2024 K Threshold Frequency. The threshold wavelength is the longest wavelength of light that can cause the ejection of electrons from the material, while the threshold frequency is the minimum frequency required. When a metal surface is exposed to a monochromatic electromagnetic wave of sufficiently short wavelength (or equivalently, above a threshold frequency), the incident radiation is absorbed.
However, the threshold has been significantly reduced. When a metal surface is exposed to a monochromatic electromagnetic wave of sufficiently short wavelength (or equivalently, above a threshold frequency), the incident radiation is absorbed.