Quantum phenomena
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Last edited time @April 8, 2024 4:22 PM
The photoelectric effect
The photoelectric effect is when a metal emits photoelectrons when
electromagnetic radiation of a certain threshold frequency is incident on the
metal’s surface.
Observations of the photoelectric effect
the photoelectric effect does not take place if the frequency of the
incident electromagnetic radiation is below a certain threshold
frequency. This means that wavelength must be less than a maximum
value since λ = fc .
The number of electrons emitted is proportional to the intensity of the
incident radiation, only if the frequency of light is above there threshold
otherwise, no photoelectrons are emitted.
Photoelectric emission occurs as soon as the incident radiation is
directed at the surface, as long as the frequency of incident waves is
higher than the threshold and regardless of intensity.
❗ These observations were a problem for scientists as they could not
be explained with the idea that light is exclusively a wave.
Explanation of the photoelectric effect
The photoelectric effect was explained using the idea of photons. This
assumed that light is composed of small packets of energy = hf . where f =
frequency of the photon and h= Planck’s constant.
Quantum phenomena 1
, This can be broken down using the wave equation v = fλinto the
following:
hc
E = hf =
λ
For more information on photons follow the link below:
🧱 Matter and radiation
This was very useful because it allowed us to say:
When light is incident onto a metal surface, an electron on the surface
absorbs a single photon of incident light and gains energy = hf .
There is a one-to-one relationship between number of emitted
photoelectrons and number of incident photons.
This is shown in the diagram below:
An electron can leave the metal surface if the energy gained from a
single photon exceeds the work function ,ϕ, of the metal.
The work function is the minimum energy required for an electron to
escape the metals surface.
Any excess energy in the electron after it has left the surface is
converted into kinetic energy.
the maximum kinetic energy of an emitted photoelectron is:
Ekmax = hf − ϕ
Quantum phenomena 2
Tags Done
Last edited time @April 8, 2024 4:22 PM
The photoelectric effect
The photoelectric effect is when a metal emits photoelectrons when
electromagnetic radiation of a certain threshold frequency is incident on the
metal’s surface.
Observations of the photoelectric effect
the photoelectric effect does not take place if the frequency of the
incident electromagnetic radiation is below a certain threshold
frequency. This means that wavelength must be less than a maximum
value since λ = fc .
The number of electrons emitted is proportional to the intensity of the
incident radiation, only if the frequency of light is above there threshold
otherwise, no photoelectrons are emitted.
Photoelectric emission occurs as soon as the incident radiation is
directed at the surface, as long as the frequency of incident waves is
higher than the threshold and regardless of intensity.
❗ These observations were a problem for scientists as they could not
be explained with the idea that light is exclusively a wave.
Explanation of the photoelectric effect
The photoelectric effect was explained using the idea of photons. This
assumed that light is composed of small packets of energy = hf . where f =
frequency of the photon and h= Planck’s constant.
Quantum phenomena 1
, This can be broken down using the wave equation v = fλinto the
following:
hc
E = hf =
λ
For more information on photons follow the link below:
🧱 Matter and radiation
This was very useful because it allowed us to say:
When light is incident onto a metal surface, an electron on the surface
absorbs a single photon of incident light and gains energy = hf .
There is a one-to-one relationship between number of emitted
photoelectrons and number of incident photons.
This is shown in the diagram below:
An electron can leave the metal surface if the energy gained from a
single photon exceeds the work function ,ϕ, of the metal.
The work function is the minimum energy required for an electron to
escape the metals surface.
Any excess energy in the electron after it has left the surface is
converted into kinetic energy.
the maximum kinetic energy of an emitted photoelectron is:
Ekmax = hf − ϕ
Quantum phenomena 2
