Simple Microscope

A simple microscope is used to see the magnified image of an object. Antonie Van Leeuwenhoek, a Dutch, invented the first simple microscope, consisting of a small single high-powered converging lens to inspect the small micro-organisms of freshwater. It is chiefly designed from the light microscope. The main property of the convex lens is to produce a virtual, erect, and enlarged image when the object is placed within the focal length. A biconvex lens is used to construct a simple microscope. A convex lens is most widely and popularly used as a reading glass or magnifying glass. Now, to obtain higher magnification, combinations of two or more convex lenses are used to form a compound microscope.

What are the Parts of the Simple Microscope?

A simple microscope is constructed with the help of various optical parts and supporting mechanical components. A few of these components are listed here along with their unique functions:

Eyepiece: It is the lens that is utilised in a simple microscope to study the samples and it is generally positioned at the top. An eyepiece of a simple microscope will have magnification power ranging from 10X to 15X.

Base: The base of a simple microscope provides support to the entire microscope structure.

Objective Lenses: The objective lenses are used to precisely view and observe the specimen/ object. The objective lenses are found with magnification ranges of 10X, 40X, and 100X. The shortest objective lens is the lower power lens while the longest lens is the higher power lens.

Diaphragm: The right quantity of light that passes through the stage will be controlled with the help of the diaphragm.

Specimen Stage: It is used for placing the slides with samples.

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Magnification of Simple Microscope

Since a simple microscope uses one objective lens, its magnification capability is extremely limited. In fact, most simple microscopes only contain a 10x magnification power. The magnifying power equation used for a simple microscope is given by the following equation:

                    M = 1 + \[ \frac{D}{F} \]

Where,

D- The shortest distance of the distinct vision 

F - The focal length of the convex lens

From the magnification formula of a simple microscope, we can say that the shorter the focal length of the lens used, the higher the magnifying power of the microscope will be.

Difference Between Simple Microscope and Compound Microscope

Now, let us state the difference between the simple and compound microscope.

Working of Simple Microscope

A simple microscope consists of a convex lens of a short focal length. The below figure shows the ray diagram which subsequently forms the image of an object (or we can say a source of light). 

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F is the focal length of the lens. An object is placed between the focal length and the centre of the curvature. A ray of light emanating from the object (source) passes through the centre of curvature of the lens (C). Another ray of light passes through the focus of the lens which lies on the other side of the lens on the principal axis. Both the rays of light enter the eye and the image is formed by tracing the rays in the backward direction as shown in Figure. The resultant image will be formed at the point of intersection of the rays. The final image is upright, enlarged and virtual. Therefore, a convex lens functions as a Simple microscope.

Simple Microscope Experiment

Here, we perform a simple experiment to calculate the magnification of a biconvex lens with a focal length F which works as a magnifying glass.

Apparatus Required

A biconvex lens of shorter focal length ‘F’ with a holder.

A newspaper article that has a small font size.

Procedure

Put the reading material under the biconvex lens and your eyes near the lens.

Move the lens slowly to the article and also move your head with the lens to observe.

As the lens is brought closer to the article, you would notice the alphabets will be small and blurred to read.

As you keep moving the lens you would see a clear and enlarged image of the alphabets printed on articles. Consider the position as ‘A’. At this position, let's say the distance between the lens and the article is ‘D’.

If you go beyond this position, the image will be magnified but blurred and difficult to read.

Using the formula, M = 1 + \[ \frac{D}{F} \] magnification can be calculated.

In this article we have discussed the simple microscope and its working principles. Also, you find the difference between the simple and compound microscope. To read more such articles, visit our website.