Question

The electron microscope was invented by
A. Robert Hooke
B. Knoll and Ruska
C. Pasteur
D. Schwann and Schleiden

Answer 1

Hint: Science and technology have progressed exponentially over the past years. This has been necessary and a key factor in the study of many substances and has also led to the discovery of new commodities. Electron microscopes are one such technology.

Complete answer:
An electron microscope is a type of microscope utilized to study and determine the ultrastructure of a broad range of biological and inorganic specimens, which include crystals, metals, cells, microorganisms, large molecules, and biopsy samples. They are used during quality control and failure analysis on industries as well. On the contrary to an optical microscope, an electron microscope as the name suggests utilizes electrons to illuminate an object instead of visible light. With the use of electrostatic and electromagnetic lenses, the electron microscope forms an image by focusing the electron beam. This entire system operates in a vacuum. An electron microscope has a high resolving power and has the ability to produce a high-resolution image on a fluorescent screen.
In 1931, the prototype electron microscope was developed by the German electrical engineer and academic professor Man Knoll and physicist Ernst Ruska. It was believed that the apparatus was the first-ever practical demonstration of the electron microscope principles.
-Louis Pasteur was a French chemist, microbiologist, and biologist who was well known for his discovery of killing bacteria from wine and milk through the pasteurization process. He is also known for producing the anti-rabies vaccine in the year 1885.
-Robert Hooke was an English architect and scientist. He was the first-ever recorded person to have visualized microorganisms using a microscope. He discovered plant cells while observing a cork through the microscope. He observed tiny boxlike cavities which he termed as cells.
-Theodor Schwann and Mathias Jakob Schleiden (a German botanist) along with Rudolf Virchow are the founders of cell theory. Theodore Schwann was a German physiologist and physician who also contributed to the discovery of Schwann cells in the peripheral nervous system and invented the term metabolism.
Therefore, the correct answer is option B, i.e., Knoll and Ruska.

Note: The electromagnetic lenses were developed in 1926 by Hans Busch and are used in the electron microscope. One of the disadvantages of an electron microscope is that they are expensive to build and maintain. They have been designed to achieve high resolutions and such microscopes are stored in buildings with special services which include magnetic field canceling systems.