An electron microscope must use electromagnet "lenses" shaped like donuts to direct the electrons onto the specimen. Why?

Question

Quizplus · Accepted Answer

Electrons are highly sensitive to interactions with other particles and can easily be scattered or deflected by them. Thus, in order to ensure that the electrons are directed onto the specimen, the use of electromagnet "lenses" (which create a magnetic field to bend the electron path) is necessary. Additionally, a vacuum is required to prevent the electrons from colliding with air molecules, which would also scatter them off course.

An Electron Microscope Must Use Electromagnet "Lenses" Shaped Like Donuts