Photoelectric effect question

In summary, the photoelectric effect is a phenomenon in which electrons are emitted from a material when exposed to light. It was first observed by Heinrich Hertz in 1887 and later explained by Albert Einstein in 1905. Its significance lies in providing evidence for the particle nature of light and leading to the development of technologies such as solar cells and photomultiplier tubes. The photoelectric effect is affected by the frequency and intensity of light, as well as the properties of the material. It is used in everyday life in technologies such as solar panels, photocopiers, and motion sensors, as well as in scientific research.
  • #1
drawar
132
0

Homework Statement


What is the maximum kinetic energy (in eV) of a photoelectron emitted when a surface, whose work function is 5eV, is illuminated by photons whose wavelength is 400 nm
1. -1.89
2. 1.89
3. 0
4. 3.1

Homework Equations


hc/(lambda)=work function + KE max


The Attempt at a Solution


After plugging numbers in the formula above, I get KE max=-1.89 eV, but I guess I must have done something wrong, since energy cannot be negative.
 
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  • #2
looks like your calculation is correct. Think about the physical significance.
 
  • #3
thank you, I've figured it out :)
since lambda > lambda0, the photoelectric effect cannot occur, then KEmax = 0
 

What is the photoelectric effect?

The photoelectric effect is a phenomenon in which electrons are emitted from a material when it is exposed to light. This emission of electrons is caused by the absorption of photons, or particles of light, by the material.

Who discovered the photoelectric effect?

The photoelectric effect was first observed by Heinrich Hertz in 1887, and was later explained by Albert Einstein in 1905.

What is the significance of the photoelectric effect?

The photoelectric effect is significant because it provided evidence for the particle nature of light, which was a major breakthrough in the understanding of quantum physics. It also led to the development of technologies such as solar cells and photomultiplier tubes.

What factors affect the photoelectric effect?

The photoelectric effect is affected by the frequency of the incident light, the intensity of the light, and the properties of the material, such as its work function and surface area.

How is the photoelectric effect used in everyday life?

The photoelectric effect is used in various technologies, such as solar panels for converting sunlight into electricity, photocopiers and digital cameras for capturing images, and motion sensors for detecting movement. It is also used in scientific research, such as in spectroscopy to study the properties of materials.

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