I teach and today I got this question from a student. I am working on electrons in the subject of electricity. And one student, and now I too, wondered how it works to see electrons.
I was working on electrons going from a negative place to a positive place. A student asked me how that was discovered? How can you see electrons? I suppose you can’t just see this under a microscope.
Answer
No, they are definitely not visible under a microscope. This has nothing to do with the magnification of the lenses used, but with the fact that an atom is much smaller than the wavelength of visible light. In order to see something we have to reflect light on it, and catch this light. This reflection is not there when the object is much smaller than the wavelength of the “light” used. That’s why radio telescopes are so big. They have to pick up radio rays, which can have wavelengths of several meters. A radio telescope should therefore have a diameter of at least a few tens of meters in order to be able to pick up those waves. The largest movable radio telescopes are 100m and more.
As mentioned, atoms are much smaller than the wavelength of visible light, namely a factor of 100 to several thousand. Atomic nuclei are another factor of 10000 times smaller, and electrons another factor… So electrons cannot be “see” directly. If they can be “see” it is indirect, through a lot of technology.
About the visibility of atoms, see : question 18818 /> And about the visibility of electrons :
http://www.science20.com/news_releases/electron_caught_on_film_for_the_first_time
Answered by
prof.dr. Paul Hellings
Department of Mathematics, Fac. IIW, KU Leuven
Old Market 13 3000 Leuven
https://www.kuleuven.be/
.