>> Also, of course, electrons that are travelling around curved
 >> parts of the circuit must experience a centripetal force.
 >> Overall, the net force on the electrons is zero, so there is
 >> no tendency for the vacuum tube to accelerate through space.

 MvdV> If it did that would be a violation of the law of
 MvdV> conservation of momentum.

Not if the power supply had an equal-but-opposite momentum to that of the
the vacuum tube.

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