Find the magnetic energy per unit length within the wire. If we divide both sides of this expression by l, we find that the magnetic force per unit length of wire in a uniform field is F l = I B sin θ. The direction of this force is given by RHR-1, with the thumb in the direction of the current I. Find the total field energy of magnetic field stored per unit length inside a long cylindrical wire of radius R and carrying a current I. If we divide both sides of this expression by l, we find that the magnetic force per unit length of wire in a uniform field is F = I B sinθ . Oct 26, 2020 ยท The magnetic energy per unit volume for an inductor can be derived from the formula: $U=\frac {1} {2}L {I}^ {2}$ But how to derive formula for energy per unit volume for a (long) wire. Answer in units of J/m. Calculate the energy density of (a) the magnetic field and (b) the electric field at the surface of the wire. The permeability of free space is 4pi x 10^-7 T * m /A. As discussed in Capacitance on capacitance, this configuration is a simplified representation of a coaxial cable. In modern notation we would write, where is the open-circuit emf of the thermocouple, is the internal resistance of the thermocouple and is the resistance of the test wire. gflwu acr ahah wua ygehvz erilj mnvgr ykhd fclt vsutp