Tag: microscope

A microscope is an instrument used to see objects that are too small to see by naked eyes. It consists the lens which magnifies the image of cells. 

In the beginning of the 19th century, Theodor Schwann (1839) established cell theory and postulated that cell is the basic unit of life. 

The cell was first discovered by Robert Hooke in 1665. He gave 60 'observations' in detail of various objects under a coarse, compound microscope. One observation was from very thin slices of bottle cork. Hooke discovered a multitude of tiny pores that he named "cells". He described a honeycomb like network of cellulae (latin for storage rooms) in cork slices.

Resolving power is the ability to distinguish two close objects as distinct. It is calculated by the formula 0.61 wavelength/ numerical aperture, where  numerical aperture is the light collecting ability of lens. It is clear that resolving power will be more if wavelength is less and numerical aperture is more. Thus, the correct answer is option A.

Antonie van Leeuwenhoek used single-lens microscopes, which he made, to make the first observations of bacteria and protozoa. His extensive research on the growth of small animals such as fleas, mussels, and eels helped disprove the theory of spontaneous generation of life.