Notes

Microscopy:

The use of the microscope is known as microscopy. The first compound Microscope was developed by Zacharias Janssen, in Holland in 1595. It was simply a tube with lenses at each end and its magnification ranged from 3X to 9X.

Important Terms used in Microscopy:

Two important terms are used in microscopy i.e. magnification and resolving power.

1. Magnification:

Magnification is the increase in the apparent size of an object and it is an important factor in Microscopy.

1. Resolving Power or Resolution:

Resolving Power or Resolution is the measure of the clarity of an image. It is the minimum distance at which two objects can be seen as separate objects.

Resolution of human Eye:

The Human Naked eye can differentiate between two points, which are at least 0.1mm apart. This is known as the resolution of the Human Eye. If we place two objects 0.05mm apart, the human eye would not be able to differentiate them as two separate objects. The Resolution can be increased with the help of lenses.

Light Microscope (LM):

A light Microscope works by passing visible light through a specimen.

Structure of Light Microscope:

It uses two glass lenses. One lens produces an enlarged image of the specimen and the second lens magnifies the image and projects it into the viewer's eye or onto photographic film.

Micrograph:

A photograph taken through a microscope is called a Micrograph.

Function Of light Microscope:

The LM cannot resolve(distinguish) objects smaller than 0.2µm. It is about the size of the smallest bacteria. The image of a Bacterium can be magnified many times, but the Light Microscope cannot show the details of its internal structure.

When we use a micrograph on the page of a book, we see some words like “LM 109X” printed along the edge of the Micrograph. It tells us that the photomicrograph was taken through a Light Microscope and that the image has been magnified 109 times.