Welcome to PhysLink.com - Your physics and astronomy online portal. Stay a while! Check out our extensive library of educational and reference materials. Also, check out our fun section!
Has the speed of propagation of a magnetic force field been measured? If so what is it?
Asked by: Colin Coulton
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