Proton Rest Energy
Rest energy of a proton (E₀ = m c²). Fundamental constant in particle physics.
MeV
0
938.272 MeV / c²
Proton / Electron
Approximate mass ratio of a proton to an electron (mₚ / mₑ).
Ratio
0
≈ 1836.15
Proton Rest (MeV)
Exact commonly used value of proton rest energy in mega-electronvolts.
MeV
0.272
CODATA Recommended
Proton Rest (GeV)
Proton rest energy expressed in giga-electronvolts (rounded).
GeV
≈ 0
0.938 GeV
LHC Proton
Beam energy per proton in the Large Hadron Collider (Run 2 / Run 3 typical).
GeV
0
6.5 – 6.8 TeV total → ~1.5 TeV per beam earlier runs
LHC Design
Design beam energy per proton of the LHC at full energy (7 TeV per beam).
GeV
0
7 TeV per beam
LHC Collision
Center-of-mass energy of proton-proton collisions at the LHC (design).
TeV
0
√s = 13 – 14 TeV
Photon Formula
Fundamental relation for photon energy: E = h f = h c / λ.
Formula
0
E = hf = hc/λ
hc Constant
Convenient value of h c in eV·nm used for quick photon energy calculations.
eV·nm
0
E (eV) ≈ 1240 / λ (nm)
Red Photon
Approximate energy of a red photon (λ ≈ 650 nm).
eV
≈ 0
≈ 1.9 eV
Green Photon
Approximate energy of a green photon (λ ≈ 550 nm).
eV
≈ 0.25
≈ 2.25 eV
Blue Photon
Approximate energy of a blue photon (λ ≈ 450 nm).
eV
≈ 0
≈ 2.76 eV
Violet Photon
Approximate energy of a violet photon (λ ≈ 400 nm).
eV
≈ 0
≈ 3.1 eV
Infrared
Typical energy of a near-infrared photon (λ ≈ 1000 nm).
eV
≈ 0.24
≈ 1.24 eV
UV Photon
Energy of an ultraviolet photon at λ = 250 nm (UVC range).
eV
≈ 0
≈ 4.96 eV
Soft X-ray
Typical energy of a soft X-ray photon (λ ≈ 1 nm).
keV
≈ 0
≈ 1.24 keV
Hard X-ray
Typical energy of a hard X-ray photon used in medical imaging.
keV
0
20 – 150 keV range
Gamma Photon
Typical energy scale of gamma-ray photons from nuclear transitions.
MeV
≈ 0
0.1 – several MeV
Electron Rest
Rest energy of an electron (useful comparison with photon and proton energies).
keV
0
511 keV
Proton vs Photon
A photon would need this energy (MeV) to match the rest energy of one proton.
MeV
0
E_photon = m_p c²
Visible Range
Approximate energy range (eV) of photons in the visible spectrum (400–700 nm).
eV
1.8 – 0.1
≈ 1.8 – 3.1 eV
Hydrogen Ionization
Energy required to ionize a hydrogen atom from its ground state (photon energy needed).
eV
0.6
13.6 eV
Silicon Bandgap
Approximate photon energy needed to create an electron-hole pair in silicon (solar cells).
eV
≈ 0.1
≈ 1.1 eV
eV to Joules
Conversion: 1 eV equals this many × 10⁻¹⁹ Joules.
×10⁻¹⁹ J
0.6
1 eV = 1.602×10⁻¹⁹ J
Quick Formula
Handy rule: Photon energy in eV ≈ 1240 divided by wavelength in nanometers.
Rule
0
E(eV) ≈ 1240 / λ(nm)
Proton Mass Energy
Mass-energy equivalence value used for protons in natural units (MeV/c²).
MeV/c²
0.272
m_p c²
Cosmic Ray Proton
Typical energy (in GeV) of common galactic cosmic-ray protons.
GeV
≈ 0–
1 – 10 GeV common
Ultra-High Energy
Energy scale (EeV) of the highest-energy cosmic-ray protons ever detected.
EeV
≈ 0
~10²⁰ eV
Photon Momentum
Photon momentum p = E / c. Even massless photons carry momentum.
Relation
0
p = E/c = h/λ
Pair Production
Minimum photon energy required for electron-positron pair production near a nucleus.
keV
0
≥ 1.022 MeV
Compton Edge
Approximate maximum energy transfer in Compton scattering for a 1 MeV photon.
MeV
≈ 0
Depends on angle
Photoelectric
Dominant process for low-energy photons interacting with atoms (complete absorption).
Process
0
E_photon → e⁻ kinetic
Proton Threshold
A photon needs at least this energy (MeV) to create a proton-antiproton pair.
MeV
0×2
≥ 1.876 GeV
Natural Units
In natural units (ℏ = c = 1), mass and energy are expressed in the same units (MeV or GeV).
System
0
E = m (when c=1)
Wavelength Rule
To find wavelength in nm from energy in eV: λ ≈ 1240 / E.
Rule
0
λ(nm) ≈ 1240 / E(eV)
Work Function
Typical work function (eV) of common metals for photoelectric effect calculations.
eV
2 – 0
Usually 2 – 5 eV
keV Photon
A 1 keV photon has this wavelength in nanometers (approx).
nm
≈ 0.24
λ ≈ 1.24 nm
MeV Photon
A 1 MeV photon has this wavelength in picometers.
pm
≈ 0.24
λ ≈ 1.24 pm
Proton Binding
Nuclear binding energies are typically a few MeV per nucleon — much smaller than proton rest energy.
Scale
0
~8 MeV per nucleon
Planck Relation
Photon energy is directly proportional to frequency: E = h f.
Law
0
E ∝ f
Solar Peak
Approximate photon energy (eV) at the peak of the solar spectrum (~500 nm).
eV
≈ 0.5
≈ 2.5 eV
Thermal Photon
Typical energy of photons emitted by a body at room temperature (thermal infrared).
meV
≈ 000
~25 meV (kT)
Rydberg
Rydberg energy — the binding energy of the electron in hydrogen (13.6 eV).
eV
0.6
13.6057 eV
Natural Unit Trick
When using ℏ = c = 1, the proton mass is simply written as 938 MeV.
Unit
0
m_p = 938 MeV
Photon-Proton
In deep inelastic scattering, high-energy photons (or virtual photons) probe the proton’s internal structure.
Process
0
DIS at HERA / EIC
Energy Units
Common hierarchy: meV → eV → keV → MeV → GeV → TeV.
Scale
0
×1000 each step
Proton vs Electron
A proton is roughly 1836 times heavier, so its rest energy is 1836 × 511 keV ≈ 938 MeV.
MeV
0
m_p ≈ 1836 m_e
Massless
Photons are massless, yet they carry energy and momentum. Protons have rest mass.
Key Diff
0
m_photon = 0
Conservation
In every interaction, total energy (including rest energy) and momentum are conserved.
Law
0
E & p conserved
Core Idea
Proton energy is dominated by rest mass at low speeds. Photon energy is purely kinetic (E = pc).
Summary
0
Rest mass vs Massless
