FIGURE 36.1 a current I flowing through a small segment dl of a wire produces at a distance r a magnetic field whose direction dH is perpendicular both to R and dL. At a radius, P, between the conductors of a coaxial cable I12πpA/ 2. Between two infinite current sheets in which the current, K, flows in opposite directions H=K×an where a. is the unit vector normal to the current sheets 3. Inside an infinitely long, straight solenoid of diameter d, having N turns closely wound h= Nilda/m 4. Well inside a toroid of radius p, having N closely wound turns H=N2rp·aA/m Applying Stokes' theorem to Ampere's circuital law we find the point form of the latter. V×H where J is the current density in amps per square meter. Time-Dependent Electric and Magnetic Fields A constant current I produces a constant magnetic field H which, in turn, polarizes the medium containing H. While we cannot obtain isolated magnetic poles, it is possible to separate the" poles"by a small distance to reate a magnetic dipole (i. e, to polarize the medium), and the dipole moment(the product of the pole strength and the separation of the poles) per unit volume is defined as the magnetization M. The units are emu/cc in the cgs system and amps per meter in the SI system of units. Because it is usually easier to determine the ma of a sample than to determine its volume, we also have a magnetization per unit mass, o, whose units are emu/g or Am /kg. The conversion factors between cgs and SI units in magnetism are shown in Table 36.1 The effects of the static and time-varying currents may be summarized as follows Static I。→[H]。→[M]。 Time-varying 山→[H]→[M]r where the suffixes"o"and"t"signify static and time-dependent, respectively e 2000 by CRC Press LLC© 2000 by CRC Press LLC 1. At a radius, r, between the conductors of a coaxial cable Hf = I/2pr A/m 2. Between two infinite current sheets in which the current, K, flows in opposite directions H = K 2 an where an is the unit vector normal to the current sheets 3. Inside an infinitely long, straight solenoid of diameter d, having N turns closely wound H = NI/d A/m 4. Well inside a toroid of radius r, having N closely wound turns H = NI/2pr · af A/m Applying Stokes’ theorem to Ampère’s circuital law we find the point form of the latter. ¹ 2 H = J where J is the current density in amps per square meter. Time-Dependent Electric and Magnetic Fields A constant current I produces a constant magnetic field H which, in turn, polarizes the medium containing H. While we cannot obtain isolated magnetic poles, it is possible to separate the “poles” by a small distance to create a magnetic dipole (i.e., to polarize the medium), and the dipole moment (the product of the pole strength and the separation of the poles) per unit volume is defined as the magnetization M. The units are emu/cc in the cgs system and amps per meter in the SI system of units. Because it is usually easier to determine the mass of a sample than to determine its volume, we also have a magnetization per unit mass, s, whose units are emu/g or Am2 /kg. The conversion factors between cgs and SI units in magnetism are shown in Table 36.1. The effects of the static and time-varying currents may be summarized as follows: where the suffixes “o” and “t ” signify static and time-dependent, respectively. FIGURE 36.1 A current I flowing through a small segment dL of a wire produces at a distance R a magnetic field whose direction dH is perpendicular both to R and dL