How Can You Explain "Electron Volts?"

[Westwind]

In reading about cosmic rays, I learned that common, low-energy cosmic rays have an energy level of one trillion electron volts (eV). Medium- and high-energy cosmic rays have levels much higher.

How can you explain the concept of "electron volts" to people (like myself) who have little or no scientific education, and who relate the idea of "voltage" to power lines and household electric current?

--Bill

[neufer]

http://en.wikipedia.org/wiki/Electronvolt

<<The first observation of a cosmic ray with an energy exceeding 10²⁰ electronvolts was made by John Linsley at the Volcanic Ranch experiment in New Mexico in 1962. Cosmic rays with even higher energies have since been observed. Among them was the Oh-My-God particle (a play on the nickname "God particle" for the Higgs boson) observed on the evening of 15 October 1991 over Dugway Proving Grounds, Utah. Its observation was a shock to astrophysicists, who estimated its energy to be approximately 3 × 10²⁰ electronvolts (50 joules)—in other words, a subatomic particle with macroscopic kinetic energy equal to that of a baseball traveling at 96 km/h (60 mph).

It was most probably a proton with a speed very close to the speed of light. To a static observer, such a proton, traveling at 1 − (5×10⁻²⁴) times c, would travel only 47 nanometers (5×10⁻²⁴ light-years) less than a light-year in one year.

Since the first observation, by the University of Utah's Fly's Eye Cosmic Ray Detector, at least fifteen similar events have been recorded, confirming the phenomenon. These very high energy cosmic rays are very rare; the energy of most cosmic rays is between 10⁷ eV and 10¹⁰ eV.>>

[Chris Peterson]

How can you explain the concept of "electron volts" to people (like myself) who have little or no scientific education, and who relate the idea of "voltage" to power lines and household electric current?

There's no connection with voltage in its common sense. It's just a unit of energy, like ergs or joules (and a rather unfortunate one that we could do without, but which is popular in a few narrow fields). A trillion eV is about 160 nanojoules.

[Westwind]

Art & Chris,

Thanks very much. This helps put it in perspective. For people without much education in science (like myself), a trillion electron volts sounds like something that would blow holes in walls because of thinking about it in terms of common electrical voltage.

--Bill