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Linear conductors with currents. Section 33. Magnitude of free energy depends on relative sense of currents. How to find forces on linear current-carrying conductors. If free energy is known as a function of shape, size, and relative positions
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Linear conductors with currents Section 33
Magnitude of free energy depends on relative sense of currents
How to find forces on linear current-carrying conductors. • If free energy is known as a function of shape, size, and relative positions • Then forces on conductors is found by differentiation with respect to the proper coordinates.
Which thermodynamic potential should we use? • It is most convenient to hold currents constant during the differentiation. • It is difficult to hold fluxes constant when the wires move. • The free energy with respect to currents is F~.
Generalized force Fq in the direction of the generalized coordinate q.
About the sign of the force vector… • Lab can be positive or negative, depending on the relative direction of the currents • Both ccw: repel • One ccw and one cw: attract
