To Study Different Parts Of Compound Microscope. | Grade Xi

Rohan Koirala - Wed Dec 27 2023

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APPARATUS REQUIRED:

Compound microscope

Prepared slide of onion peel

Prepared slide of human cheek cells

Glass slides

Cover slips

Lens paper

Immersion oil (if available)

CHEMICAL REQUIRED

Methylene blue or safranin (for staining the cells)

THEORY:

A compound microscope is a type of microscope that uses two or more lenses to produce a magnified image of a specimen. The objective lens, which is located at the bottom of the microscope, gathers light from the specimen and focuses it on the image plane. The ocular lens, which is located at the top of the microscope, then magnifies the image produced by the objective lens.

The magnification of a compound microscope is calculated by multiplying the magnification of the objective lens by the magnification of the ocular lens. For example, a microscope with a 10x objective lens and a 10x ocular lens would have a total magnification of 100x.

PROCESS:

Place the prepared slide of onion peel on the stage of the microscope.
Secure the slide in place with the stage clips.
Turn on the microscope and adjust the light intensity.
Start with the lowest magnification objective lens (usually the 4x objective lens).
Focus the microscope by turning the coarse focus knob until the image of the specimen is clear.
Fine-tune the focus by turning the fine focus knob.
Observe the specimen and make a drawing of what you see.
Repeat steps 5-7 for the higher magnification objective lenses (usually the 10x, 40x, and 100x objective lenses).
If you are using immersion oil, place a drop of oil on the specimen before using the 100x objective lens.
After you are finished observing the specimen, remove the slide from the stage and clean the microscope lenses with lens paper.

OBSERVATIONS:

At low magnification (4x objective lens), the onion peel cells appear as small, rectangular or square cells.

As the magnification is increased, the cells become more detailed. The cell walls, nucleus, and cytoplasm can be seen.

At high magnification (100x objective lens), the nucleus can be seen in great detail. The nuclear membrane, nucleolus, and chromatin can be seen.

The human cheek cells appear as large, round cells. The cell membrane, nucleus, and cytoplasm can be seen.

The nucleus of the human cheek cells is larger and more complex than the nucleus of the onion peel cells.

The cytoplasm of the human cheek cells contains many small organelles, such as mitochondria and lysosomes.

OBSERVATION TABLE:

Objective Lens	Magnification	Structures Observed
4x	40x	Cell walls, nucleus, cytoplasm
10x	100x	Cell walls, nucleus, cytoplasm, nucleolus
40x	400x	Nucleus, nuclear membrane, nucleolus, chromatin
100x	1000x	Nucleus, nuclear membrane, nucleolus, chromatin, mitochondria, lysosomes

Calculation:

The magnification of a compound microscope is calculated by multiplying the magnification of the objective lens by the magnification of the ocular lens.

For example, a microscope with a 10x objective lens and a 10x ocular lens would have a total magnification of 100x.

RESULTS:

The compound microscope is a powerful tool that allows us to see the microscopic world. We were able to observe the cells of an onion peel and human cheek cells in great detail.

PRECAUTIONS:

Always handle the microscope with care.

Do not touch the lenses with your fingers.

Only use immersion oil with the 100x objective lens.

Clean the microscope lenses with lens paper after each use.

Store the microscope in a safe place when not in use.