principles, application, parts,advantages & magnification

1. COMPOUND
MICROSCOPE & IMAGE
FORMED BY CONVEX
LENSES.

2. IMAGE FORMATION BY CONVEX LENSES:
• When an object is placed at infinity, the real image is formed at the focus. The size
of the image is much smaller as compared to that of the object.

3. • When an object is placed behind the center of curvature, the real image is formed between the
center of curvature and focus. The size of the image is same as compared to that of the object.

4. • When an object is at the center of curvature, the real image is formed at the other center of
curvature. The size of the image is same as compared to that of the object.

5. • When an object is placed in between the centre of curvature and focus, the real image is the
formed behind the center of curvature. The size of the image is smaller as compared to that of
the object.

6. • When an object is placed at the focus, a real image is formed at infinity. The size of the
image is much larger as compared to that of the object.

7. • When an object is placed in between focus and pole, a virtual image is formed. The size of
the image is larger as compared to that of the object.

8. • THE TERM “COMPOUND” IN COMPOUND MICROSCOPES
REFERS TO THE MICROSCOPE HAVING MORE THAN ONE
LENS.
• DEVISED WITH A SYSTEM OF COMBINATION OF LENSES,
A COMPOUND MICROSCOPE CONSISTS OF TWO OPTICAL
PARTS, NAMELY THE OBJECTIVE LENS AND THE OCULAR
LENS.

9. WORKING PRINCIPLE OF THE COMPOUND
MICROSCOPE
 The specimen or object, to be examined is usually mounted on a
transparent glass slide and positioned on the specimen stage between
the condenser lens and objective lens.
 A beam of visible light from the base is focused by a condenser lens
onto the specimen.
 The objective lens picks up the light transmitted by the specimen and
creates a magnified image of the specimen called the primary image
inside the body tube. This image is again magnified by the ocular lens
or eyepiece.

12. PARTS OF COMPOUND MICROSCOPE
Mechanical parts
• Used to support and adjust the parts
Magnifying parts
• Used to enlarge the specimen
Illuminating parts
• Used to provide light

13. MECHANICAL PARTS
• Base or foot- basal structure that supports all the remaining parts of the
microscope.
• Pillar- small, strong vertical projection developing from the foot.
• Arm- curved and strong structure used for handling the entire
instrument.
• Inclination joint- joint at which the arm is attached to the pillar of the
microscope. Used for tilting the microscope.
• Stage- flat rectangular plate where slide is placed. A hole is present in

14. MAGNIFYING PARTS
• Ocular/ eye piece- lens found at top of the body tube which functions
to further magnify the image produced by objective lens.
• Objectives- are the primary optical lenses on a microscope. They
range from 4x- 100x.

15. ILLUMINATING PARTS
• Mirror- located beneath the stage and has concave plane surface to gather and
direct light on order to illuminate the object.
• Iris diaphragm- regulates the amount of light necessary to obtain a clearer view of
the object
• Condenser- set of lenses between the mirror and stage that concentrates light rays
on the specimen.

17. MAGNIFICATION
Magnification is the ability to view an object larger.
• The magnification of a compound microscope is given by:
M=
𝐷
𝑓 𝑒
x
𝐿
𝑓 𝑜
where,
D= least distance of distinct vision(25 cm)
L= length of the microscope tube
Fo= focal length of the objective lens
Fe= focal length of the eye piece
The highest total magnification is 1000x for a compound microscope.

18. APPLICATIONS
• A compound microscope is of great use in pathology labs so as to identify diseases.
• Various crime cases are detected and solved by drawing out human cells and examining them under
the microscope in forensic laboratories.
• The presence or absence of minerals and the presence of metals can be identified using compound
microscopes.
• Students in schools and colleges are benefited by the use of a microscope for conducting their
academic experiments.
• It helps to see and understand the microbial world of bacteria and viruses, which is otherwise
invisible to the naked eye.
• Plant cells are examined and the microorganisms thriving on it can be ascertained with the help of a
compound microscope. Thereby, a compound microscope has proved to be crucial to biologists.

19. ADVANTAGES
• Simplicity and its convenience.
• A compound light microscope is relatively small, therefore it’s easy to use and
simple to store, and it comes with its own light source.
• Because of their multiple lenses, compound light microscopes are able to reveal a
great amount of detail in samples.

20. THANK YOU