Build the electronvolt from an electron crossing one volt, then practice choosing eV, keV, MeV, GeV, or TeV instead of joules for particle-scale energies.

Use scientific notation and metric prefixes to compare atoms, nuclei, protons, Higgs-scale masses, and LHC energies by order of magnitude. Practice deciding when a factor of 10, 1,000, or a million matters more than exact decimals.

Trace why E = mc² lets particle physicists quote electron, proton, and Higgs boson masses in MeV or GeV. Read the c = 1 convention and translate between eV, eV/c², and ordinary mass units without thinking mass has disappeared.

Apply the previous explanations in a guided problem.

Use ℏ and ℏc ≈ 197 MeV·fm to connect energy, wavelength, time, and distance. Reason why higher-energy particles can probe smaller structures, and why femtometers and inverse GeV show up together.

Check whether a particle-physics expression has the right kind of units before trusting it. Convert simple final answers back to SI when needed, while keeping natural units as the working language.

Apply the previous explanations in a guided problem.

Check your understanding with a short quiz.

Review this chapter with practice based on your mistakes.