Naked Science Forum

General Science => General Science => Topic started by: Ron Hughes on 14/01/2011 16:55:06

Title: Does a charged particle moving at 95% of the speed of light emit radiation?
Post by: Ron Hughes on 14/01/2011 16:55:06

Does a charged particle moving at 95% of the speed of light emit radiation? Let's assume there is no radiation anywhere along it's path.

Title: Re: Does a charged particle moving at 95% of the speed of light emit radiation?
Post by: Bored chemist on 15/01/2011 00:21:06

It will if the refractive index of the medium is more than about 1.05
http://en.wikipedia.org/wiki/Cherenkov_radiation

Title: Re: Does a charged particle moving at 95% of the speed of light emit radiation?
Post by: Ron Hughes on 18/01/2011 16:18:07

If true doesn't that suggest it would also radiate, albeit with enormously long wavelengths, at one meter per second?

Title: Re: Does a charged particle moving at 95% of the speed of light emit radiation?
Post by: imatfaal on 18/01/2011 18:29:25

That's the askaryan effect - when a particle (not necessarily charged)travels through a very dense dielectric faster than the speed of light through that particular material.  BC was pointing out the much more observable cherenkov radiation - there are lovely photos of the blue glow in nuclear reactors on the page he provided.

Askaryan effect happens through a creation of charged particles which then radiate in the microwave or radio - it has only been observed in solids, and seems to be a way of detecting neutrinos http://www.ps.uci.edu/~anita/.

I don't understand the "one meter per second" bit - the radiation will travel at whatever the speed of light is in that material, which is highly unlikely to be as low as 1 m/s