text: A pair of parallel circular coils that share a common axis named for this physicist induce a nearly uniform magnetic field and is a precursor to the solenoid.
full_question: A pair of parallel circular coils that share a common axis named for this physicist induce a nearly uniform magnetic field and is a precursor to the solenoid. Like Kelvin, he studied instabilities in hydrokinetic solutions, but published first. His "decomposition" expresses a field as a divergence-free part plus a curl-free part. A function named for him is constant for a given canonical ensemble, is denoted A, and equals the work an isochoric, isothermal system can do. For 10 points--identify this mentor to Hertz, Boltzmann, and Michelson, a German scientist who, like Josiah Gibbs, gave his name to a "free energy."
first_sentence: A pair of parallel circular coils that share a common axis named for this physicist induce a nearly uniform magnetic field and is a precursor to the solenoid.