Chapter 26, Problem 54P

Go Figure 26-36a shows a rod of resistive material. The resistance per unit length of the rod increases in the positive direction of the x axis. At any position x along the rod. the resistance dR of a narrow (differential) section of width dx is given by dR = 5.00.V dx. where dR is in ohms and x is in meters. Figure 26-36b shows such a narrow section. You are to slice off a length of the rod between x = 0 and some position x = L and then connect that length to a battery with potential difference V = 5.0 V (Fig. 26-36c). You want the current in the length to transfer energy to thermal energy at the rate of 200 W. At what position x = L should you cut the rod?

Figure 26-36 Problem 54.