How We Came to Know the Cosmos:
Light & Matter

by Dr Helen Klus

# Chapter 33. List of symbols

### 33.0.1 Numerical Constants

 c Speed of light = 299,792,458 m/s (first used in Chapter 2) e Euler’s number = 2.718 (to 3dp) (first used in Chapter 17) h Planck’s constant = 6.626×10-34 Js (to 3 dp) (first used in Chapter 8) ħ ħ = h/2π, where h is Planck’s constant (first used in Chapter 16) i Imaginary unit = √-1 (first used in Chapter 16) R Rydberg constant = 1.097×107 m-1 (to 3dp) (first used in Chapter 10) π π = C/D = 3.142 (to 3 dp), where C is the circumference of a circle, C = 2πr, and D is the diameter of a circle, D = 2r (first used in Chapter 7) σ Stefan-Boltzmann constant = 5.670×10-8 kg s-3 K-4 (to 3dp) (first used in Chapter 7)

### 33.0.2 Other symbols

 A Amplitude (first used in Chapter 3) d Distance (first used in Chapter 4) E Energy (first used in Chapter 8) F Flux (first used in Chapter 7) KE Kinetic energy (first used in Chapter 17) k k = 2π/λ, where λ is the wavelength (first used in Chapter 17) L Angular momentum (first used in Chapter 15) L Luminosity (first used in Chapter 7) ℓ Azimuthal quantum number (first used in Chapter 11) m Mass (first used in Chapter 8) m Magnetic quantum number (first used in Chapter 11) N0 The initial quantity of a radioactive substance (first used in Chapter 6) Nt What remains of a radioactive substance after time t (first used in Chapter 6) n Refractive index (first used in Chapter 2) n Shell number (first used in Chapter 10) P Momentum matrices (first used in Chapter 16) p Momentum (first used in Chapter 15) PE Potential energy (first used in Chapter 17) Q Position matrices (first used in Chapter 16) r Radius (first used in Chapter 7) T Temperature (first used in Chapter 7) t Time (first used in Chapter 4) t1/2 Half-life (first used in Chapter 6) v Velocity (first used in Chapter 2) x Position (first used in Chapter 16) Z Atomic number, equal to the number of protons in an atom’s nucleus (first used in Chapter 10) Δ ‘Change in’ (first used in Chapter 4) θi Angle of incidence (first used in Chapter 2) θr Angle of reflection (first used in Chapter 2) θrefr Angle of refraction (first used in Chapter 2) λ Wavelength (first used in Chapter 7) ν Frequency (first used in Chapter 7) Φ Work function (first used in Chapter 8) Ψ(x,t) Wave function (first used in Chapter 17) ω Angular frequency, ω = 2πν, where ν is frequency (first used in Chapter 17)