A sample of SiO2 nanospheres with radius of 75 nm is found to have a drift velocity vd = 1.2 m/s in an electric field of 2.40 V/cm, in an aqueous solution with an ionic strength of 10 mM. The particles move towards the positive electrode. 2a. Calculate the electrophoretic mobility of these particles 2b. Choose an appropriate model and calculate a value for the potential of the particles.