6,736 research outputs found
On the significance of polarization charge and isomagnetic surface in the interaction between conducting fluid and magnetic field
From the frozen-in field lines concept, a highly conducting fluid can move
freely along, but not traverse to, magnetic field lines. We discuss this topic
and find that in the study of the frozen-in field lines concept, the effects of
inductive and capacitive reactance have been omitted. When admitted, the
relationships among the motional electromotive field, the induced electric
field, the eddy electric current, and the magnetic field becomes clearer and
the frozen-in field line concept can be reconsidered. We emphasize the
importance of isomagnetic surfaces and polarization charges, and show
analytically that whether a conducting fluid can freely traverse magnetic field
lines or not depends solely on the magnetic gradient in the direction of fluid
motion. If a fluid does not change its density distribution and shape (can be
regarded as a quasi-rigid body), and as long as it is moving along an
isomagnetic surface, it can freely traverse magnetic field lines without any
magnetic resistance no matter how strong the magnetic field is. When our
analysis is applied, the origin of the magnetic field of sunspots can be
interpreted easily. In addition, we also present experimental results to
support our analysis.Comment: 12 pages, 12 figures, 4 table
Thermodynamics of scalar-tensor theory with non-minimally derivative coupling
With the usual definitions for the entropy and the temperature associated
with the apparent horizon, we show that the unified first law on the apparent
horizon is equivalent to the Friedmann equation for the scalar--tensor theory
with non-minimally derivative coupling. The second law of thermodynamics on the
apparent horizon is also satisfied. The results support a deep and fundamental
connection between gravitation, thermodynamics, and quantum theory.Comment: 12 pages, no figure, minor correction
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