What are two types of electron microscopes, and how do they work?

Scanning electron microscope (sem):  an electron beam scans the surface of a specimen (coated with gold) that excites electron from the specimen which are detected and translated into an image that is three-dimensional. It is used to study the topography of a specimen

Transmission Electron microscope (TEM):a beam of electrons is passed through a thin section of specimen that is stained with atoms or heavy metals and electromagnets acts as lenses that focus the image onto a screen or film. It is used to study the internal structure of a specimen--cells