Question

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

Search

Loading



Click here to get
a FREE ride with Uber!


Click here to
sign up for Birchbox






Science Quote

'The mathematician's patterns, like the painter's or the poets, must be beautiful; the ideas, like the colours or the words, must fit together in a harmonious way. Beauty is the first test: there is no permanent place in the world for ugly mathematics.'

Godfrey Hardy
(1877-1947)
Science Sidebar | Science Education Articles
10 Ways to Keep Your Kids Interested In Science

Young children are natural scientists: they ask questions, pick up sticks and bugs outside, and are curious about the world around them. But as they get a bit older, many kids gradually lose their interest in science. They might see it as just another task at school, something that doesn't apply to their lives. Of course nothing could be further from the truth, so here are ten ways you can remind your kids that science is everywhere. Most of these are fun for adults, too! Continue reading ...

Top Selling

Here are our physics & astronomy bestsellers:
Deluxe Water Rocket Set
Mini Plasma Ball
KonusScience 5 Way Microscope Kit
3D Magnetic Field Tube
Scorpion, Ant, Wasp and Flower Bug
Solar Radiometer
Alnico Bar Magnet - 6 inch Long
Weather Station 4M Kit
Periscope
Cherry Wood Levitron

Sponsors

USC University of Southern California Dornsife College Physics and Astronomy Department McMaster University Physics and Astronomy Department