If the power line and the telephone line described in Prob. 4.6 arc in the same horizontal plane and the distance between the nearest conductors of the two lines is 18 m, use the result of Prob. 4.6(a) to find the mutual inductance between the power and telephone circuits. Also, find the 60-Hz voltage per kilometer induced in the telephone line when 150 A flows in the power line.
Prob. 4.6
The energy density (that is, the energy per unit volume) at a point in a magnetic field can be shown to be B2/2μ, where B is the flux density and μ is the permeability. Using this result and Eq. (4 .10), show that the total magnetic field energy stored within a unit length of sol id circular conductor carrying current I is given by μl2/16π. Neglect skin effect, and thus verify Eq. (4.1 5)
