Take the 2-minute tour ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free, no registration required.

I know that electromagnetic waves induce electric currents in conductors and that's the basis for radio, wi-fi etc.

I also know that light is also an electromagnetic wave. So, can light induce a current in a conductor (like a metal wire? or a coil?). And, if the answer is yes, is the same visible for other high-frequency waves (X-rays, gamma)?

I heard about the photoelectric effect, but it seems related to the particle theory of light (photons transferring their energy to electrons).

So, do high-frequency electromagnetic waves generate electric currents? Is it possible to measure them? Is the skin effect relevant here?

share|improve this question
    
Just a side remark: voltage is induced, not current. –  Rafael Reiter Jan 25 '13 at 16:23

1 Answer 1

up vote 3 down vote accepted

You only get generation of an oscillating EMF in the antenna if the frequency of the EM radiation is less than the plasma frequency of the metal. For higher frequencies the electrons in the antenna can't move fast enough to respond to the EM oscillation so you can't generate a potential difference.

The frequency of green light is around 600THz, and Googling suggests the plasma frequency of silver is about the same (there seem to be a wide range of values). So visible light is right on the edge of generating an EMF and shorter wavelength EM radiation won't generate an EMF.

share|improve this answer
1  
You neglected to mention that if the energy of the photon must be higher than the work function of the metal, excess energy may be carried away by the ejected electron by the photoelectric effect. –  Will Cross Jan 25 '13 at 17:36

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.