Constants & Conventions

The whole chapter runs on a small kit of numbers and a habit of picking the right units. Work in electron-volts and nanometres, lean on hc = 1240 eV·nm, and switch to MeV and femtometres once you reach the nucleus. This is the quick reference behind the ⊙ Constants button on every page.

§01

The quantum toolkit

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§02

Energy ⇄ wavelength, at a glance

One relation — E = hc/λ with hc = 1240 eV·nm — ties a photon's energy to its wavelength across the whole spectrum, from visible light to hard X-rays. Slide the energy and read the wavelength (and the band it lands in). The same slider shows the Lorentz factor γ climbing as a speed approaches c.

photon energy

{{ cvE }}

wavelength λ

{{ cvLam }}

slide energy{{ cvBand }}

λ(nm) = 1240 / E(eV) · equivalently λ(pm) = 1240 / E(keV). Higher energy ⇒ shorter wavelength.

Lorentz factor γ

{{ cvGamma }}

speed v

{{ cvBetaPct }}% c

slide speedβ = {{ cvBeta }}

γ = 1/√(1 − β²) ≥ 1. It's ≈ 1 for everyday speeds and diverges as v → c — the reason nothing massive reaches light speed.

§03

Units you'll actually use

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§04

One formula per module

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