Photon

Содержание и основные понятия

The quant of the electromagnetic field is a photon. It has no mass of rest, moves in a vacuum at a speed of c and carries energy and impulse.
GEF · 11 grade
PIF · Baseline
Interactive model
Photon
Quantum
luminous pressure
Comtonian dispersion
01
The physical picture
What happens and what boundaries the model has.
Main message
The quant of the electromagnetic field is a photon. It has no mass of rest, moves in a vacuum at a speed of c and carries energy and impulse.
Photon energy is growing with frequency.
The pulse explains the pressure of the light.
The absorption and radiation occur in whole quants.
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.
E
=
h
ν
=
h
c
λ
E=h\nu=\frac{hc}{\lambda}
E
=
h
ν
=
λ
h
c
​
Photon energy
p
=
h
λ
p=\frac{h}{\lambda}
p
=
λ
h
​
Photon pulse
Review of the situation
Shortwave photon has more energy and impulse than longwave.
04
Links and application
In the real world
Shortwave photon has more energy and impulse than longwave.
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 "Photones" through a model, not just a formula.
Outcome 2
Clear and correctly use the terms: photon, quant, pressure of light.
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.
Photon
Quantity of electromagnetic field with energy h and pulse h/.
Quantum
The minimum discrete portion of the physical value in the process.
luminous pressure
Pressure generated by the transmission of the irradiation pulse during absorption or reflection.
Comtonian dispersion
Non-resilient photon scattering on a free or loosely connected electron with an increased photon wave length.
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.
E
=
h
ν
=
h
c
λ
E=h\nu=\frac{hc}{\lambda}
E
=
h
ν
=
λ
h
c
​
Postulate or Model
Photon energy.
The following is an indication of the definition, experience or law from which this entry arises and where it is applicable.
E
=
h
ν
E=h\nu
E
=
h
ν
Quantum model assigns photon energy proportional to frequency.
c
=
λ
ν
c=\lambda\nu
c
=
λ
ν
For an electromagnetic wave in a vacuum, frequency and length are bound by the speed of light.
ν
=
c
λ
⇒
E
=
h
c
λ
\nu=\frac{c}{\lambda}\quad\Rightarrow\quad E=\frac{hc}{\lambda}
ν
=
λ
c
​
⇒
E
=
λ
h
c
​
The elimination of frequency gives an expression of energy over wave length.
Conditions:
One photon in the vacuum; . . is the vacuum-wire length, .
Monitoring:
The dimensions of both parts shall coincide; the result shall be checked for sign, order and limit case.
p
=
h
λ
p=\frac{h}{\lambda}
p
=
λ
h
​
model effect
Photon pulse.
The following is an indication of the definition, experience or law from which this entry arises and where it is applicable.
E
2
=
p
2
c
2
+
m
2
c
4
E^2=p^2c^2+m^2c^4
E
2
=
p
2
c
2
+
m
2
c
4
The relativistic bond of energy and impulse is also applicable to the massless particle.
m
=
0
⇒
E
=
p
c
m=0\quad\Rightarrow\quad E=pc
m
=
0
⇒
E
=
p
c
For a photon with zero rest mass, the energy is pc.
E
=
h
c
λ
⇒
p
=
h
λ
E=\frac{hc}{\lambda}\quad\Rightarrow\quad p=\frac{h}{\lambda}
E
=
λ
h
c
​
⇒
p
=
λ
h
​
The quantum energy of the photon gives it a pulse.
Conditions:
The photon in the vacuum; p is the pulse module directed along the distribution, . . is the vacuum wave length.
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
You can't put the formula on any situation just because it's a coincidence of letters. The key condition of this topic is that photon energy grows with frequency.
How to Check the Mind
The pulse explains the pressure of the light. Then check the units, vector direction, and behaviour of the result at zero or very large parameter.
Σ
Conclusion on the topic
Photon
The quant of the electromagnetic field is a photon. It has no mass of rest, moves in a vacuum at a speed of c and carries energy and impulse.
Photon energy is growing with frequency.
The pulse explains the pressure of the light.
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.