Photoelectric Effect - Maximum Wavelength

AI Thread Summary
The photoelectric effect occurs when light of a certain wavelength strikes a metal surface, causing it to emit electrons. Light with a wavelength of 450 nm has sufficient energy to overcome the metal's work function, leading to electron emission, while 650 nm light does not provide enough energy. The threshold frequency, which is the minimum frequency required for photoelectric emission, is directly related to the work function of the metal. The relationship between wavelength and frequency is crucial, as energy is inversely proportional to wavelength. Understanding these concepts is essential for grasping the principles of quantum mechanics.
LotusTK
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Hi, I am currently revising photoelectric effect, and i have this question:

A metal surface at zero potential emits electrons from its surface if light of wavelength of 450 nm is directed at it but not if light of 650nm is used. Explain why photoelectric emission happens with light of wavelength 450nm but not with light of wavelength 650nm

All i know is that the wavelength must be below a certain maximum value equal to the speed of light divided by the threshold frequency.

I don't know why this is, can someone explain why? Thanks.
 
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