FRANK TECHNOLOGY

  Most electric toasters not only grill slices of bread, they also pop them up when ready. While the slices rest on a spring-loaded rack, electric heating elements toast the bread. At the same time, a bimetallic strip heats and expands. One of the two metals in this strip expands more quickly than the other, causing the strip to curve. As it bends, it completes an electrical circuit and activates an electromagnet. The magnet attracts a catch, releasing the spring that holds the rack down in the toaster. The elements switch off, and the toasted slices pop up.  

Optical microscopes from a magnified image by using lenses to bend light. Some special purpose microscopes used in industry and research  are designed for observing particular material, such as living cells. They produce magnifications of up to about 2000. Electron microscopes produce magnifications of as much as 50 million, although 2 million is more typical. Their images are formed by means of electrons focused by magnetic lenses. There are two main types: scanning electron microscopes (SEMs) scan electrons back and forth across the surface of specimen; transmission electron microscopes (TEMs)  transmit electron through a thin slice of the specimen.