MadSci Network: Physics |
You have to be careful in using the EM field momentum vector for static fields. In order for the field momentum to exert an impulse on any object, there must be a traveling wave that reflects from (or is absorbed by) the object. In the calculation for sunlight moving a solar sail, it is the reflection of the traveling wave that produces the impulse. This can also be calculated using the force on currents in the sail induced by the oscillating fields of the wave. If the wave isn't moving or oscillating in time, there will be no force.
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