Threshold Frequency: Equation & Electron Release

In summary, the equation used to solve for the threshold frequency is W=hf_{0}, where W is the work function, h is Planck's constant, and f_{0} is the threshold frequency. The threshold frequency is the minimum amount of energy required to free an electron from the nucleus. The energy of the photon should be sufficient to knock out the electron, but not quite enough to completely remove it from the metal. This is why the full equation for the photoelectric effect includes a second term for the kinetic energy of the ejected electron.
  • #1
Gogsey
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What is the equation used to solve for the threshold frequency?

Is the threshold frequency the minimum amount of energy requird to free an electron from the nucleus?
 
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  • #2
[tex]W=hf_{0}[/tex]

where [itex]W[/itex] is the work function, [itex]h[/itex] is Planck's constant, and [itex]f_{0}[/itex] is the threshold frequency. I believe the answer to your second question is yes.
 
  • #3
We talk of threshold frequency because the energy of the photon is h*f. That energy should be sufficient enough to knock out the electron.
 
  • #4
rgshankar76 said:
We talk of threshold frequency because the energy of the photon is h*f. That energy should be sufficient enough to knock out the electron.

To be precise this is just sufficient energy to bring an electron to the surface but not quite to knock it out of the metal. (Again this depends on how you interpret "knock out"). Thats why in the so called Einstein equation for photoelectric effect, there's a second term which accounts for the kinetic energy of the ejected photoelectron...if this term were zero, the electron would--in principle--stay there.
 
  • #5
That is true. The full equation is

[tex]E_{photon}=W+E_{K}_{max}[/tex]

As you can see, the equation for [itex]W[/itex] as a function of threshold frequency is derived from this by setting the kinetic energy of the photoelectron to zero.
 
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1. What is threshold frequency?

Threshold frequency is the minimum frequency of light required to eject electrons from the surface of a metal. It is different for different metals and is determined by the work function of the metal.

2. How is threshold frequency related to the work function?

The threshold frequency and the work function of a metal are directly proportional. This means that as the work function increases, so does the threshold frequency.

3. What is the equation for threshold frequency?

The equation for threshold frequency is: f0 = W/h where f0 is the threshold frequency, W is the work function, and h is Planck's constant.

4. What happens when the frequency of light is below the threshold frequency?

When the frequency of light is below the threshold frequency, no electrons will be emitted from the metal surface, regardless of the intensity of the light. This is because the energy of the photons is not enough to overcome the work function of the metal.

5. How does the intensity of light affect the threshold frequency?

The intensity of light does not affect the threshold frequency. It only affects the number of electrons emitted, not the energy of each individual electron. The threshold frequency remains the same regardless of the intensity of light.

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