War, the magnification obtainable with a microscope was limited by the wavelength of visible light. This is because two points on a microscope specimen cannot be distinguished from each other if they are not at least as far apart as half the wavelength of the light used to illuminate them. By using a beam of electrons instead of light as the illuminant, virtually any wavelength can be used by controlling the velocity of the electrons electrically. Thus, by subjecting a beam of electrons to a potential of 10 000 volts, a wavelength of about 10-9 centimetres is obtained, compared to visible wavelength of the order of 5 x 10-5 centimetres. Glass lenses cannot be used with electron microscopes, instead a system of magnetic lenses is used for focusing the beam, and the resulting image is photographed on a special type of photographic plate. With the tremendous magnifications possible with this instrument, objects as small as individual viruses can be clearly photographed and observed.Teacher: Your time is up. Now let’s do some exercises. The first is to find English equivalents for the following words and expressions in the text. Correct your translation, if you have mistakes
