# Is electrostatics the cause of radio waves?

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1. Nov 14, 2014

### J3N0VA

That is probably a badly worded question but I understand electrostatics and I want to send simple but efficient radio signals. If I switch on a strong charge in one place it'll effect a charge away from it depending on "Coulomb's law". How is this equation expanded to explain more efficient production of electromagnetic signals?

2. Nov 14, 2014

### Staff: Mentor

Electrostatics is a simplified case of the more general "electromagnetism". The rules governing electric charges, electrical and magnetic effects, and any other related issues are given by Maxwell's Equations. These equations incorporate many other electrical/magnetic laws into a set of four equations that we can use to solve any problems regarding electromagnetism. In formulating these equations, Maxwell showed that radio waves, light, and other similar types of radiation are all electromagnetic waves with different wavelengths/frequencies.

The most efficient way of sending a radio signal is to simply use an appropriate transmitter for the wavelength/frequency you are sending.

3. Nov 14, 2014

### homeomorphic

To get EM waves, you need electrodynamics, not electrostatics. It's not a Coulomb's law effect. In fact, Coulomb's law breaks down if you have accelerating charges. One of the keys is Maxwell's "displacement current". This is sort of a ghost current that would go through a capacitor while it's charging up, in lieu of the actual current that's being held up there. It's sort of a symmetric law to Faraday's law which says that a changing magnetic field produces an electric field. Maxwell came along and said a changing electric field also produces a changing magnetic field. Changing magnetic field gives rise to changing electric and vice versa. So, you end up with a kind of chain reaction, which is an electromagnetic wave. It results when charges are accelerated.