Instruments, Microscope

Simple Microscope: Working Principle, Uses, Parts, and their Functions.

Hey, in this article we will learn about “Simple Microscope” and its working principle, applications, and parts. Before you proceed with the...

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MN Editors
This article writter by MN Editors on July 05, 2020

Microbiology Notes is an educational niche blog related to microbiology (bacteriology, virology, parasitology, mycology, immunology, molecular biology, biochemistry, etc.) and different branches of biology.

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Simple Microscope
Simple Microscope

Hey, in this article we will learn about “Simple Microscope” and its working principle, applications, and parts.

Before you proceed with the simple microscope, first of all, you can check my previous article “Parts of Microscope with their Functions and Working Principle” to get a basic idea about a microscope’s parts and their function, and how a microscope works.

Now let’s jump to our parent article;

Definition of Simple Microscope

  • Simple Microscope refers to those microscopes consist of a single lens to enlarge an object through angular magnification alone, giving the viewer an erect enlarged virtual image.
  • These types of microscopes are used different types of lense for magnification such as; magnifying glass, loupes, and eyepieces.
  • A Simple Microscope is a type of optical Microscope or light Microscope.
  • This was the first microscope ever created.
  • It was invented by Antony van Leeuwenhoek in the 17th century. He combined a convex lens and a holder for specimens. 

Principle of Simple Microscope

All simple microscopes works on a principle, if you place a tiny object or specimen in front of a simple microscope’s lens within its focus, a virtual, erect and magnified image of the object is formed at the least distance of distinct vision from the eye held close to the lens.

Working Mechanism of Simple Microscope

Figure: Working Mechanism of Simple Microscope | Image Source:

This ray diagram in below, explains how simple microscopes is working;

  1. A small object AB which is to be magnified is placed between the principal focus F’ and optical center C of the convex lens.
  2. Now, a ray of light AO parallel to a principal axis which is coming from point A of the object passes through the focus F along the straight line OX after getting refracted by the convex lens.
  3. A second ray of light AC coming from the point A of the object passes through the optical center C of the convex lens along the straight line CY.
  4. As is clear from the figure that the two rays i.e. OX and CY are diverging rays so these rays can intersect each other only at point A’ when produced backward.
  5. Now, on drawing A’B’ perpendicular from point A’ to the principal axis, we get the image A’B’ of the object which is virtual, erect, and magnified.

Magnification of a simple Microscope

The magnifying power of simple microscopes is given by: 

M    =     1    +    D/F 

Where,  D = the least distance of distinct vision

                 F = focal length of the convex lens

It should be noted,

  • Smaller the focal length of the lens, greater will be its magnifying power. 
  • This microscope has a maximum magnification power of  10, which means the specimen will appear 10 times larger by using the simple microscopes of maximum magnification.

Parts of Simple Microscope with diagram

simple microscope diagram
Figure: simple microscope diagram | Image Source:

Simple microscopes are consist of two important parts, includes;

  1. The Mechanical Parts
  2. The Optical Parts

1. The Mechanical Parts

The Mechanical Parts support the optical parts and help in their adjustment for focusing the object. They include the following components;

a. Metal Stand

  • It has a heavy base plate and a vertical rod fitted to it.

Function of Metal Stand

  • Metal Stand provides support and stability to other parts of the microscope.

b. Stage

  • It’s refers to a rectangular metal plate fitted to the vertical rod.
  • Stage also has a central hole for light to pass from below. 
  • Some simple microscopes have a pair of slanting wings projecting from both sides of the stage which provide support to hand for manipulating the object.

Function of stage

  • The specimen slide place over it to be observed.

c. Base: The bottom portion of simple microscope is known as the base. This portion provides supports to the microscope.

d. Stage clips: located at the stage of simple microscope; helps to hold the specimen slides in the proper place.

e. Adjustment screw: It is used to adjust the focus on specimen.

2. The Optical Parts

The optical parts help in magnification and visualization of specimen. This part is consist of these following components;

1. Mirror

  • It has a plano-convex mirror, which is located is below the stage to the vertical rod by means of a frame.


  • The primary function is to focus the surrounding light on the object being examined.

2. Lens

  • Simple microscopes has a biconvex lens which is located above the stage, to the vertical rod, by means of a frame. 
  • For proper focusing, the lens can be moved up and down by the frame.


  • It magnifies the size of the object and the enlarged virtual image formed is observed by keeping the eye above it.

A modern simple microscope contain these following parts;

  • Eyepiece: A set of lenses, located at the top of microscope, which used to visualize the samples. It has a magnification power of 10X to 15X.
  • Tube: It connect the eyepiece to the objective lenses.
  • Revolving nose-piece: The Revolving nose-piece or turret holds the objective lenses and it can rotate during the study of sample.
  • Fine adjustment knob: The Fine adjustment knob is used to focus on oil.

Applications of Simple Microscopes

There are present different uses of simple microscopes such as;

  1. In Jewelry making shop, Jewelry makers used it to visualize the magnified view of the small parts of the jewelry.
  2. In the Watchmaking industry, watchmakers used it to magnify a tiny part of the watch.
  3. In the Agriculture sector, it is used to magnify various particles of various types of soils.
  4.  Palmist used a simple microscopes to visualize the lines of the hands.
  5. In Dermatology, a dermatologist or skin specialist used it to check for various skin diseases.
  6. In Microbiological experiments, a microbiologist used it for examining and studying microscopic fungi, algae, and other biological specimens that are difficult to visualize using the naked eyes.
  7. It also used to visualize the details of stamp and engravings.
  8. It also used to check the texture of fibers or threads of a cloth.

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YouTube video

FAQ of Simple Microscopes

  1. What is the definition of a simple microscopes?
  2. What is the uses of simple microscopes?
  3. What is simple microscope magnification?
  4. When was the simple microscope invented?
  5. What was the first microscope called?
  6. Who discovered microscope first time?
  7. What Are The Parts Of Simple Microscope?
  8. What is the working principle of a Simple Microscope?


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Microbiology Notes is an educational niche blog related to microbiology (bacteriology, virology, parasitology, mycology, immunology, molecular biology, biochemistry, etc.) and different branches of biology.

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