Final answer:
An electron microscope forms an image of a specimen using a beam of electrons, providing greater magnification and resolving power compared to light microscopes. There are two main types, TEM and SEM, both of which require the specimen to be dead as the preparation process kills the cells.
Step-by-step explanation:
An instrument that forms an image of a specimen using a beam of electrons rather than light is called an electron microscope. Electron microscopes provide much greater magnification and higher resolving power compared to light microscopes. There are two common types: the Transmission Electron Microscope (TEM) and the Scanning Electron Microscope (SEM).
The TEM works by transmitting a beam of electrons through a specimen to form an image. It requires specimen preparation that kills the cells and the samples to be very thin. TEM offers an extremely high resolution that can exceed 0.5 Å and magnification above 50 million times. In contrast, the SEM scans the surface of a specimen with a focused beam of electrons to provide high-detail, three-dimensional images. The SEM does not require the specimen to be thin and can magnify images up to 2,000,000x. However, SEM has a lower resolution compared to TEM.
Both types of electron microscopes operate in a vacuum to allow the electron beam to move effectively and, unfortunately, cannot be used to view live specimens since the preparation process for viewing kills the cells.