Everything Science Grade 12

CHAPTER 12. WAVE NATURE OF MATTER 12.3

Figure 12.2: The imageof the polio virus usinga transmission electronmicroscope.

The structure of an optical and electron microscope are compared in figure 12.3. While
the optical microscopeuses light and focuses using lenses, the electron microscope
uses electrons and focuses using electromagnets.

electron source

magnetic lens

target

objective lens

projector lens

screen

electron microscope

light source

condenser lens

target

objective lens

eyepiece lens

optical microscope

Figure 12.3: Diagram ofthe basic components ofan optical microscope and an electron
microscope.

Electron microscopes are very useful as they are able to magnify objects to a much
higher resolution. Thisis because their de Broglie wavelengths are somuch smaller
than that of visible light. You hopefully remember that light is diffracted by objects