Study of various parts of a compound microscope

Aim

Study of various parts of a compound microscope.

Material Required

Compound microscope, practical notebook, pencil, sharpners, eraser, etc.

Theory

In structure and function, we can compare the microscope with an human eye. Both have lenses and in both the images of object are formed. Organisms even smaller than 1 mm are studies in the laboratory. Beside this, stained and mounted slides of various types of tissues and cells are studied because these microscopic structure cannot be seen by naked eyes, hence, microscope is used for the observation of such structure. We can see the magnified image of the object with the help of microscope. The power to magnify an object is called magnifying power. The ratio of magnified image and original image is called the magnifying power of the instrument.

Magnifying power of microscope =

The size of magnified image by microscope / The size of the normal image by naked eye

Two types of microscope are used in biology laboratory :

1. Simple (dissecting) microscope.
2. Compound microscope.

Procedure

Observe the given instrument carefully and draw the labelled diagram of the instrument on your practical notebook.

Structural observation

It is used to observe very minute objects. It magnifies the object about 400-600 times. It has the following parts:

1. Eye-piece - It is fitted into the draw tube. Slide is observed through it by the left eye.
2. Body tube - It is connected to the arm. It is cylindrical having draw tube and an eye piece on the upper part and two or three objectives on the lower part. It can be moved up and down as desired.
3. Nose piece - It is round, plate like and fitted below the body tube. Two or three objectives lenses are fitted into it. The high power and low power objective lenses can be rotated (move) with the help of it.
4. Objective lens - It consists of high power and low power lenses which magnify an object several times its original size.
5. Stage - It is attached with the arm and is flat like a plate. It has a hole through which the slide may be observed.
6. Stage clip - Two clips are attached on the posterior end on both the sides of the stage which support the slide.
7. Condenser - It is situated below the hole of the stage. Light is focussed on the slide by it.
8. Iris diagram - It is fitted below the condenser. Path of light rays is adjusted by it.
9. Mirror - It is round concave mirror situated slightly above the base and is attached with the arm which send light towards slide or material after reflecting it.
10. Coarse adjustment - It helps in focussing the slide by moving the body tube up and down.
11. Fine adjustment - The slide is placed under low high power objective lens and focussed by its slow upper or er movement.
12. Base - It is horse shoe-shaped and made of solid iron. It supports microscope.
13. Arm - It connects the base and body tube of the microscope. It is curved in shape and helps in handling the microscope.
14. Inclination point - Base and arm are jointed with each other through it. The microscope may be tilted towards the user through this joint only, whenever required.

Uses

It is used in observing micro-organisms, different sections and histological structures.

Viva Questions and Answers

Question 1: Why do we use microscope ?

Answer: We use microscope to see the magnified image of the object.

Question 2: How many sets of lenses do magnify object in th/e compound microscope ?

Answer: Two, i.e., eye-piece (Ocular) and objective.

Question 3: Who invented microscope ?

Answer: Robert Hooke was the first person who invented microscope in 1665. But later on Leeuwenhoek made it better.

Question 4: How many and what types of lenses are there in simple (dissecting) microscope ?

Answer: The simple (dissecting) microscope has only one convex lens.

Question 5: What is meant by magnifying power ?

Answer: The ability to magnify an object is called magnifying Power.

Question 6: What are the main microscope used in the laboratory ?

Answer: Two microscope are mainly used in the laboratory: (i) simple (dissecting) microscope and (ii) Compound microscope.