Chapter 31, Problem 31.6DQ

Equation (31.9) says that υ_ab = L di/dt (see Fig. 31.8a). Using Faraday’s law, explain why point a is at higher potential than point b when i is in the direction shown in Fig. 31.8a and is increasing in magnitude. When i is counterclockwise and decreasing in magnitude, is υ_ab = L di/dt still correct, or should it be υ_ab = −L di/dt? Is υ_ab = L di/dt still correct when i is clockwise and increasing or decreasing in magnitude? Explain.