Has the speed of propagation of a magnetic force field been measured? If so what is it?
Asked by:
Colin Coulton
Answer
The term magnetic force field implies the application of a force on a distant
object, say a piece of iron, by a magnetic field.
In order to generate a magnetic field that can be said to propagate, it is
necessary to produce a changing field by turning on an electromagnet or removing a
magnet from a magnetic shield such as a superconducting box. Changing magnetic
fields are also produced around all radio transmitter antennas due to the changing
current flowing in them.
When a magnetic field is changing, it is always accompanied by a transverse
electric field, i.e., it is an electromagnetic wave. The relationships between
changing magnetic and electric fields are summarized in the well-known Maxwell's
equations.
Click here for a more detailed mathematical derivation and description.
The speed of electromagnetic waves is certainly known and is defined to be exactly
299,792,458 m/s in vacuum (same as the speed of light).
Answered by:
Scott Wilber, President, ComScire - Quantum World Corporation
'Physics is mathematical not because we know so much about the physical world, but because we know so little; it is only its mathematical properties that we can discover.'