The different components of ζapp/ζ (see Equation (2)) as a function of the dimensionless zeta potential, -ζF/(RT). The first three subplots (left to right, then top to bottom) plot numerator, the first term in the denominator, the second term in the denominator and the third term in the denominator of the factor enclosed in square brackets in Equation (2), and the last subplot plots ζapp/ζ, i.e. the factor enclosed in square brackets.