Chapter 32, Problem 28P

GO Figure 32-35a shows the current i that is produced in a wire of resistivity 1.62 × 10^–5 Ω · m. The magnitude of the current versus time r is shown in Fig. 32-35b. The vertical axis scale is set by i_s= 10.0 A, and the horizontal axis scale is set by t_s = 50.0 ms. Point P is at radial distance 9.00 mm from the wire’s center. Determine the magnitude of the magnetic field ${\stackrel{\to }{B}}_i$ at point P due to the actual current iin the wire at (a) t = 20 ms, (b) t = 40 ms, and (c) t = 60 ms. Next, assume that the electric field driving the current is confined to the wire. Then determine the magnitude of the magnetic field ${\stackrel{\to }{B}}_{id}$ at point P due to the displacement current i_d in the wire at (d) t = 20 ms, (e) t = 40 ms, and (f) t = 60 ms. At point P at t = 20 s, what is the direction (into or out of the page) of (g) ${\stackrel{\to }{B}}_i$ and (h) ${\stackrel{\to }{B}}_{id}$?

Figure 32-35 Problem 28.