**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 = h2π, where h is Planck’s constant (first used in Chapter 16) |

i | Imaginary unit = √-1 (first used in Chapter 16) |

R |
Rydberg constant = 1.097×10^{7} m^{-1} (to 3dp) (first used in Chapter 10) |

π |
π = CD = 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 = 2πλ, 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) |

N_{0} |
The initial quantity of a radioactive substance (first used in Chapter 6) |

N_{t} |
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) |

t_{1/2} |
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) |

θ_{i} |
Angle of incidence (first used in Chapter 2) |

θ_{r} |
Angle of reflection (first used in Chapter 2) |

θ_{refr} |
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) |

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