h , k , l= Miller Indices ;    

R₁ = Rate of effusion (or diffusion ) of the first gas ; R₂ = Rate of effusion (or diffusion) of the second gas; M₁ = Mass of the first gas; M₂= Mass of the second gas

K = Rate Constant;  A = Frequency Factor;  E_A = Activation Energy;  T = Temperature; R = Universal Gas Constant ;

v= Reaction Rate ; v_max =Maximum Rate ; [S] = Substrate Concentration ; K_m = Michaelis Constant

λ= Initial wavelength of the photon before scattering; λ' = Final wavelength of the photon after scattering; θ = Scattering angle; h= Plank's constant ; m_e = Rest mass of an electron;   c = speed of light in vaccum 

λ= De Broglie Wavelength ; m= mass ; v= velocity ; h = Plank's constant ( 6.6262 x 10^-34 Js)

E^o= Standard Electrode Potential ;  R = Gas Constant ; F = Faraday's Constant ; K_eq = Equilibrium Constant ;  T = Temperature ; n = Number of electrons involved in the cell reaction ; 

E= Equivalent Weight; A= Atomic Weight ; V= valency ; 

W = Weight produced at an electrode ; z = Electrochemical equivalent  i = Current ;  t = Time ; 

Λ^o_eq = Equivalence Conductivity at infinite dilution. λ^o₊ & λ ^o_- = Equivalence Conductivity of Cation and Anion;