Photo Effect

Содержание и основные понятия

The light is emitted from the surface by external photo-effects, the energy of the individual electron is determined by the frequency and the number of electrons by the intensity of the light, which is the same as the other electrons.
GEF · 11 grade
PIF · Baseline
Interactive model
Photo-effect
exit work
Red border
locking voltage
01
The physical picture
What happens and what boundaries the model has.
Main message
The light is emitted from the surface by external photo-effects, the energy of the individual electron is determined by the frequency and the number of electrons by the intensity of the light, which is the same as the other electrons.
There is a red boundary: there is no below the threshold frequency of the photo-effect.
The increase in intensity does not compensate for the insufficient frequency.
Photon energy is transmitted to one electron with a portion.
How to reason
First, name the system and the interaction, then select the values, and only then write down the law. The formula works within the model's assumptions.
02
Laws and values
Symbols should be read as a relationship of values, not as a recipe for substitution.
h
ν
=
A
вых
+
m
v
max
⁡
2
2
h\nu=A_{\text{вых}}+\frac{mv_{\max}^2}{2}
h
ν
=
A
of which:
​
+
2
m
v
m
a
x
2
​
​
Einstein equation
e
U
з
=
m
v
max
⁡
2
2
eU_{\text{з}}=\frac{mv_{\max}^2}{2}
e
U
c/
​
=
2
m
v
m
a
x
2
​
​
locking voltage
Review of the situation
If the frequency is below the threshold, even a very bright light does not strike the electrons in single-featon school mode.
04
Links and application
In the real world
If the frequency is below the threshold, even a very bright light does not strike the electrons in single-featon school mode.
Model verification
Compare the prediction with observation, evaluate the units, the order of magnitude and the influence of the factors not taken into account. Disparity does not always mean an error of law: often idealization is no longer sufficient.
C
What needs to be understood
Outcome 1
Explain the physical meaning of the theme "Phot effect" through the model, not just through the formula.
Outcome 2
Clear and correct use of terms: photo effects, exit work, red boundary.
Outcome 3
Indicate the conditions for the applicability of the law, verify units and limit cases.
T
Terms of the topic
The definition should indicate the physical meaning, not a substitute for a domestic synonym.
Photo-effect
The release of electrons by a substance during the absorption of electromagnetic radiation.
exit work
The minimum energy required for the electron to leave the substance.
Red border
The lowest frequency or the largest wave of light at which photo-effects are still possible for the substance.
locking voltage
Reverse voltage at which the most rapid photo-electronics stop.
F
Origin and conclusion of the formulas
The fundamental law cannot be "proven" by algebras: for each record, it is stated whether it is a definition, an experimental law, or a model effect.
h
ν
=
A
вых
+
m
v
max
⁡
2
2
h\nu=A_{\text{вых}}+\frac{mv_{\max}^2}{2}
h
ν
=
A
of which:
​
+
2
m
v
m
a
x
2
​
​
model effect
Equation of Einstein.
The following is an indication of the definition, experience or law from which this entry arises and where it is applicable.
E
γ
=
h
ν
E_\gamma=h\nu
E
γ
​
=
h
ν
One electron absorbs the energy of one photon according to the quantum model of light.
A
вых
A_{\text{вых}}
A
of which:
​
Part of the energy is spent on releasing the electron from the substance; the minimum work is equal to the output.
h
ν
=
A
вых
+
K
max
⁡
=
A
вых
+
m
v
max
⁡
2
2
h\nu=A_{\text{вых}}+K_{\max}=A_{\text{вых}}+\frac{mv_{\max}^2}{2}
h
ν
=
A
of which:
​
+
K
m
a
x
​
=
A
of which:
​
+
2
m
v
m
a
x
2
​
​
The law of energy conservation gives maximum kinetic energy to photo-electronics.
Conditions:
A single phototonic external effect, not lower than the red boundary; non-relativist electrons, Avochs refer to the material and surface condition.
Monitoring:
The dimensions of both parts shall coincide; the result shall be checked for sign, order and limit case.
e
U
з
=
m
v
max
⁡
2
2
eU_{\text{з}}=\frac{mv_{\max}^2}{2}
e
U
c/
​
=
2
m
v
m
a
x
2
​
​
model effect
Locking voltage.
The following is an indication of the definition, experience or law from which this entry arises and where it is applicable.
A
поля
=
−
e
U
з
A_{\text{поля}}=-eU_{\text{з}}
A
Fields
​
=
−
e
U
c/
​
The locking field does negative work on an electron flying to the anode.
K
кон
=
K
max
⁡
−
e
U
з
K_{\text{кон}}=K_{\max}-eU_{\text{з}}
K
Cot
​
=
K
m
a
x
​
−
e
U
c/
​
By law, changes in kinetic energy in the field reduce the energy of the fastest photo-electronic.
K
кон
=
0
⇒
e
U
з
=
K
max
⁡
=
m
v
max
⁡
2
2
K_{\text{кон}}=0\quad\Rightarrow\quad eU_{\text{з}}=K_{\max}=\frac{mv_{\max}^2}{2}
K
Cot
​
=
0
⇒
e
U
c/
​
=
K
m
a
x
​
=
2
m
v
m
a
x
2
​
​
At locking voltage, even the fastest electrons stop.
Conditions:
The locking voltage is determined by the cut-off of the photo; e is the electron charge module, the contact potentials are ignored.
Monitoring:
The dimensions of both parts shall coincide; the result shall be checked for sign, order and limit case.
!
Model boundaries and typical errors
Error: Forget model condition
The formula cannot be transferred to any situation simply because of the overlap of letters. The key condition of this topic is that there is a red boundary: there is no below the threshold frequency of the photo-effect.
How to Check the Mind
The increase in intensity does not compensate for the insufficient frequency. Then check the units, vector direction, and the behaviour of the result at zero or very large parameter.
Σ
Conclusion on the topic
Photo Effect
The light is emitted from the surface by external photo-effects, the energy of the individual electron is determined by the frequency and the number of electrons by the intensity of the light, which is the same as the other electrons.
There is a red boundary: there is no below the threshold frequency of the photo-effect.
The increase in intensity does not compensate for the insufficient frequency.
Any numerical result shall be accompanied by a unit, a sign and an explanation of its physical meaning.
The content is consistent with the FRP on Physics of the OS/OSS 2025 and the subject matter of the current lines of the PNP: I. M. Peryškin and co-authors (7–9), G. J. Mäkishev and coauthors (10–11), and with the lines "Engineers of the Future" and V. A. Kasyanov. The original texts are not reproduced, the text of the textbooks is not reproduced.