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Expert: Daniel Mazur - 10/13/2010


Question
while studying light, why we prefer wavelength why not frequency?

Answer
Hello Zafeer,

this is because when handling visible light, people compare certain linear dimensions of the instruments to the "length" property of light, which is the wavelength. Typically, a diffraction grating needs to have a certain spacing between the lines, which is approximately the same as the wavelength of the visible light. Apertures of optical microscopes cannot be smaller than the visible light wavelength, or the light cannot go through - this imposes the limit of resolution of optical microscopes and gives us reasons to use other microscopes (i.e. ones not based on visible light) for resolution in nanoscale.

It is not only visible light that is described with wavelength. In radio communication there is a traditional division of electromagnetic radiation into "long waves", "middle waves", "short waves" and "very short waves". These were established, because of the respective sizes of the corresponding dipole antennae. Infrared radiation (see infrared spectroscopy) is, on the other hand, frequently measured by "wavenumber", which is the inverse of the wavelength.

Cheers,
Daniel

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Questions anyone (teenager, undergrad, graduate, professional) may ask on physics, mathematics or inorganic chemistry. Questions may concern subjects themselves or a possible future career in them, if you need advice on a school or hobby project, or you just came across a question that is beyond your current curriculum. I answer bare textbook problems sometimes, but I reserve the the right to redirect you to Physics-Physics section. The kind of questions I like to answer: I just started having science classes at school and they seem difficult, but I enjoy them. Where do I find more information on this, which is not in textbooks but still comprehensible to me? Just leaving high school, and I feel science is really the thing for me. Can you recommend a school and an undergrad program suitable to my inclinations? I am in my second undergraduate year in Physics. We learned the basics of universe expanding this year, the Hubble constant and all that, but invited speakers that gave talks on astrophysics in our department seemed not to agree with this model at all. Is it of any use at all? I am building a [materials research] experimental device for my masters/doctorate thesis and I have the following problem:... I have tried ..., but it still doesn't work. Where might the problem be?

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