the number of atoms or molecules in a mole of a substance, equal to 6.022 52 × 10 23
lambert
the cgs unit of illumination , equal to 1 lumen per square centimetre
lepton number
a quantum number describing the behaviour of elementary particles , equal to the number of leptons present minus the number of antileptons . It is thought to be conserved in all processes
L'Hospital's rule
the theorem that for the quotient of two functions satisfying certain conditions on a given closed interval , each having infinite limit or zero as limit at a given point, the limit of the quotient at the given point is equal to the limit of the quotient of the derivatives of each function