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Light microscope and electron microscope differ in the magnification range, which is related to the wavelength. Both light radiation and electron radiation spread in waves. In the case of light radiation, we see different colors depending on how long the wave is. Blue, for example, has a very short wavelength, and red a very long wavelength. In simple terms, the color blue could be imagined as tightly curled hair, and red as almost smooth, loose natural waves. But our eyes can only see a small part of all wavelengths. The UV light, which is invisible to us, has an even shorter wavelength than the color blue and much below this wavelength we find electron radiation.
Explanation for children: The light microscope uses light radiation and the electron microscope uses electron radiation. The fact that you can see much smaller structures with the electron microscope is related to the wavelength. Both types of radiation behave similarly - they move in waves. When we draw a sun, we usually paint lines as sunrays. This is not entirely true, because solar and electron rays are actually wave-shaped, like curly hair. The wavelength describes the distance from one wave to the next. If the hair is very curly, the wavelength is short, because the next wave is not far away from the last one. If the hair is only a little wavy, the wavelength is very long, because it takes a very long time until the next wave comes. The problem with light microscopy is that the wavelengths of visible light are relatively long (380 - 780 nanometers). If we now want to look at something that is, for example, only 250 nanometers in size, the light cannot capture the living being and can not create an image. This is why the electron microscope is used for very small structures, because electron radiation has a much smaller wavelength.