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EXPERIMENT No. 1 A:TO STUDY THE DIFFERENT PARTS OF A COMPOUND MICROSCOPE. DESCRIBE EACH PART BRIEFLY. (Diagram not required in examination)
THEORY:
Compound microscope is an optical instrument which is used to see micro-organisms which cannot be seen by naked eye and works on the principle of magnifying glass.
REQUIREMENTS:
Compound microscope.
PROCEDURE:
Take a compound microscope and observe its different parts, draw its diagram and label it.
OBSERVATION AND DESCRIPTION OF PARTS OF MICROSCOPE:
- BASE:
Lower metallic horseshoe shaped foot of microscope is called base.
FUNCTION:
Base provides firm support and stability to the microscope. - ARM:
It is a curved metallic rod which connects the body tube to the base.
FUNCTION:
Arm supports the body tube and is used to handle the microscope. - BODY TUBE:
It is a metallic tube fitted with eye-piece lens at its upper end and revolving nose piece at its lower end on which objective lenses are screwed.
FUNCTION:
It is used to adjust the distance between object and objective which in turn focuses the object clearly. - INCLINATION JOINT:
It is an adjustable or movable joint between arm and base of microscope.
FUNCTION:
It is used for adjusting the angle of microscope to a suitable level. - STAGE:
It is a metallic horizontal, square or rectangular area under the objective.
FUNCTION:
Slide is placed on the stage for viewing. - SUB-STAGE:
It is a small piece below the stage which has two components.
A. IRIS OR DIAPHRAGM:
It is a folded circular screen having a hole in the center, which can be increased or decreased by a clip.
FUNCTION: It is used to adjust the intensity of light.
B. CONDENSER: It is a convex lens, placed between the holes of the stage.
FUNCTION: It condenses the light. - STAGE CLIPS:
Two shiny adjustable clips present on the stage one on either side of aperture.
FUNCTION:
Stage clips are used to hold the slide in place. - APERTURE:
Hole in the center of stage is called aperture.
FUNCTION:
Aperture allows light coming from the mirror, for better viewing the specimen. - REFLECTOR:
It is a movable circular frame having concave mirror on one side and plane mirror on the other side fitted in an adjustable circle bellow the stage.
FUNCTION:
It is used to reflect light in proper direction. - EYE-PIECE LENS OR OCULAR:
The upper end of body tube holds a small tube fitted with a double convex lens called eye- piece. The eye- piece lenses are of different magnifying power.
FUNCTION:
In compound microscope eyepiece serves as a magnifying lens and forms magnified image. - NOSE PIECE:
It is a rotating part of microscope at the bottom of the body tube.
FUNCTION:
It holds the objective lens. - OBJECTIVE LENSES:
Nose piece holds small tubes fitted with double convex lens called objective.
FUNCTION:
Objective forms a real, inverted and magnified image of object. - COARSE ADJUSTMENT KNOB:
It is a large, round knob on the side of microscope.
FUNCTION:
It is used for focusing the specimen, it may move either the stage or the upper part of microscope. - FINE ADJUSTMENT KNOB
It is small round knob on the side of microscope.
FUNCTION:
It is used to fine-tune the focus of specimen after using the coarse adjustment knob.
PRECAUTIONS:
- Handle microscope carefully.
- Adjust the reflecting mirror to get an illuminated screen.
- First focus the object under low power by using coarse adjustment screw (knob).
- After focusing under low power, focus the object under high power by using fine adjustment screw (knob).
DIAGRAM
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All answers of ch# 5 are taken from google
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