MicroWorlds Contents | Advanced Light Source | Berkeley Lab

How Is Seeing Related to Wavelength?


Can you see atoms by looking through a visible-light microscope?

Why don't microwaves escape through the holes in a microwave oven's door?

It is impossible to use electromagnetic radiation to "see" an object if the wavelength of the radiation is larger than that object. Therefore, you cannot see atoms by using visible light, because atoms are much smaller than visible-light wavelengths. Visible-light waves range from 0.4 to 0.7 micrometer (4000 to 7000 angstroms), whereas an atom is only a few angstroms in size.

For the same reason, microwaves, also a kind of electromagnetic radiation, don't escape through the holes in the microwave oven door. The holes are smaller than the wavelength of microwaves, which measure about 120 millimeters (or 12 centimeters). Therefore, the microwaves don't "see" the holes. But visible light, which has much smaller wavelengths, can easily pass through the holes. So we can look through the holes and see the food cooking.

  Return to Electromagnetic Radiation
  Return to "The Advanced Light Source: A Tool for Solving the Mysteries of Materials."

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