APP2: Modern Physics Variables

α (radiation)

alpha particle; a free helium nucleus: two protons and two neutrons (charge of +2)

β-

Beta particle; a free electron (charge of -1)

β+

Beta anti-particle; a free positron (charge of +1)

γ

Gamma particle; a free high-energy photon (charge of 0)

λ (decay)

decay constant (s⁻¹)

t_1/2

half-life (s)

N (decay)

number of particles

E (nuclear)

energy from converted mass (J or MeV)

m (nuclear)

mass defect: expected mass - actual mass (kg or amu)

c

speed of light in a vacuum (m/s) (Extra Credit: 3×10⁸ m/s)

E (modern)

energy of photon (J or eV) (Extra Credit:

1eV = 1.60×10^-19J)

h

Planck's constant; quantizes energy and momentum

(Extra Credit: 6.63×10^-34J*s or 4.14×10^-15eV*s)

f (modern)

frequency of light/photon (Hz)

Φ (modern)

work function: minimum energy for photon to eject electron (J or eV)

K_max

maximum energy of photoelectrons (J or eV)

p (modern)

momentum of a photon (kgᐧm/s)

λ (modern)

de Broglie wavelength (m)

b

Wein's constant (Extra Credit: 2.90×10^-3m*K)

T (modern)

absolute temperature (K)

P (modern)

rate at which energy is emitted by a blackbody (W or J/s)

A (modern)

surface area of blackbody (m²)

σ (modern)

Stefan-Boltzmann constant (Extra Credit: 5.67×10^-8 W/m²K⁴)