The inability of this theory’s ideal form to explain reconnection led to the creation of Sweet-Parker and Petschek models. For 10 points each:
[10m] Name this formalism whose ideal version ignores terms proportional to diffusivity, resulting in a simpler form of Ohm's Law and the induction equation.
ANSWER: magnetohydrodynamics [or MHD; accept ideal magnetohydrodynamics or ideal MHD]
[10h] By analogy to rubber bands, the stretching, twisting, and folding of these constructs creates a dynamo. Álfven's theorem constrains the size of these surfaces by implying that a certain quantity is conserved.
ANSWER: magnetic flux tubes
[10e] Ideal MHD is a good approximation when the magnetic analogue of this quantity is large. Fluids transition from laminar to turbulent flow when this value is around a few thousand.
ANSWER: Reynolds number [accept magnetic Reynolds number]
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