Chapter 30 2. drawing 20. drawing 12. (mu_0)h/2 parallel to sheet; perp to current 32. (a) 171 microT; 137 microT (b) 0.138 microWb (c) rate of heat production = 1.54 J/s 38. 168 nT 40. B_square = (mu_0)(2sqrt2)I/(pi)L; B_square/B_circle = 0.9 46. for ratio of 0.90, x = 0.270 R; for ratio of 0.10, x = 1.91 R 52. zero 54. (a) 25 V/s (b) 5.65 Nm²/Cs; 5 microA 58. (mu_0)h²/2 attractive 62. 0.603 N attractive Chapter 31 4. 92.3 nW 6. graph 12. at t = 0, I = 0; at t = T/4, I is clockwise; at t = T/2, I = 0; at t = 3T/4, I is clockwise 16. Br_0(alpha)/R_0(1+(beta)t); clockwise looking down with B out of page, and current loop in plane of page 30. 24.1 microV away from the wire 42. I'=(2(pi)r²(mu_0)nI_0/Rt_0)e^(-t/t_0) 44. inside E = -R(mu_0)n(omega)I_0cos(omega t)/4; outside E = -R(mu_0)n(omega)I_0cos(omega t)/4 46. R = 11.3 cm 50. 3.59 m/s 54. (a) left (b) counter-clockwise (c) 1.8 A Chapter 32 12. 9.29 x 10^{-24} Am² Chapter 33 2. L/volume = (mu_0)n² 8. L_eq = L_1 + L_2 18. L = ((mu_0)N²h/2(pi))ln((R+w)/R); for R>>w, L = (mu_0)N²A/l 32. (a) L = 9.01 mH (b) U = 11.3 microJ 40. (a) u_B = (mu_0)I²r²/8(pi²)a^4 (b) U_B/length = (mu_0)I²/16(pi) 42. 351 - 3510 ohms 46. I=(V/R)e^(-Rt/L) 50. 1.52x10^{13} Hz 52. Imax = q/sqrt(LC); t_max = (n+(1/2))(pi)sqrt(LC) where n=0-infinity 56. 1.79 ohms 60. proof; E = Q_0²/2C 62. Imax = 224 mA; Qmax = 200 microC; Imin = Qmin = 0 64. proof Chapter 34 2. 67.8 M$ 4. 0.417 A 18. (a) t = (n+(1/2))8.33 ms + 2.78 ms; n = 0 to infinity (b) t = (n+(1/2))8.33 ms - 1.39 ms; n = 0 to infinity 40. C = 1/2(pi)fR; L = R/2(pi)f 47. ANSWER IN BOOK IS WRONG!! (a) (EMF_m)²R/2(omega²)L² --> 0 as omega --> infinity (b) (1/2)(EMF_m)²R(omega²)C² --> 0 as omega --> 0 NOTE: the book uses V_0 for what I call EMF_m Chapter 14 14. (a) 2.09 m (b) 0.318 Hz (c) .4 m (d) 3.14 s (e) 3 m^{-1} Chapter 15 8. (a) proof (b) A = 10 cm; f = 1.5 Hz Chapter 35 12. proof 16. B = (0.667nT)cos(kz-wt) in the -i direction with k = .0314/m and w = 9.42 M rad/s; where w stands for omega 22. E = 0.268 V/m @ 5 km, B = 0.894 nT; E = 0.0134 V/m @ 100 km, B = 44.7 pT 24. 3.33 mN 26. 192 W/m² 32. <u> = 2.90 nJ/m³ ; Erms = 18.1 V/m; Brms = 60.4 nT 45. ANSWERS IN BOOK ARE WRONG! At least according to the picture in my copy of the text. The correct answers are: (a) j (b) i (c) -k (d) dir of E = -j, B = -i, S = -k NOTE: No information is given that allows us to distinguish between the two sets of answers. You could just as correctly have (a) -j (b) -i with the E and B in (d) made positive. 48. 0.211 52. I = (I_0)0.096