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Q & A: Water waves and light waves

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Most recent answer: 06/04/2015
Q:
Suppose I drop a pebble in a pond, causing a wave. I next drop a small twig on the wave. The twig can ride the wave and move outwards. Similarly, why does an electron NOT move under the influence of the electric field associated with a light wave?
- Sandeep Sharma (age 39)
Dallas, TX
A:

Hello Sandeep,

Unless the water wave is nonlinear like a tsunami, the twig will simply bounce up and down and not be transported.  An electron can be moved by an incident light wave;  consider the photo-electric effect as an example where an electron is ejected from an atom.

LeeH

 

The electron will wiggle back and forth in the electric field and also be pushed a little in the direction the light wave is going by the radiation pressure from the combined electric and magnetic fields. mw


(published on 06/04/2015)

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