II. Calculation and Derivation (3 questions, 9 pts) 1. (2 pts) Weber-Fechner law describes the relationship between a physical stimulus and perception of the stimulus. Use P to represent perception and S to represent stimulus, write the governing differential equation for dp, ds, and S. A constant (k) should be in the equation. (1 pt) Assuming that P = 0 when S = So, which is the threshold stimulus, solve the differential equation to obtain P as a function of S. (1 pt)