Microscope: Types and Functions

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Questions and Answers

What is the origin of the word 'microscope'?

From the Latin word (micro)= tiny and (scopeo)= to observe
From the French word (microscopie)= small view
From the English word (micro)= minute and (scope)= to examine
From the Greek word (micron)= small and (skopein)= to look at (correct)

How are microscopes broadly classified based on the source of illumination?

Confocal microscope and transmission electron microscope
Fluorescence microscope and phase contrast microscope
Optical microscope and scanning microscope
Light microscope and electron microscope (correct)

What is the function of the ocular lens in a compound microscope?

To separate objects in the sample
To further magnify the image produced by the objective lens (correct)
To fix and stain the sample
To provide illumination for the sample

Why are samples fixed, sectioned, and stained for observation under a light microscope?

To enhance contrast and visibility of the specimen (C) Signup and view all the answers

What is the maximum distance by which objects can be distinguished using a light microscope?

0.2 μM (D) Signup and view all the answers

What is the function of the diaphragm in a microscope?

Controls the amount of light on the slide/specimen (D) Signup and view all the answers

What is the purpose of the coarse adjustment knob on a microscope?

Moves the stage up and down (quickly) for focusing your image (C) Signup and view all the answers

Where are the objective lenses of a microscope held?

Revolving nose piece (C) Signup and view all the answers

What does magnification in a microscope refer to?

The ratio of the image size to the actual size (B) Signup and view all the answers

How is total magnification determined in a microscope?

By multiplying the eyepiece lens by the objective lens (A) Signup and view all the answers

What is the main factor determining magnification in a microscope?

The objective lens (D) Signup and view all the answers

What is the function of the revolving nose piece in a microscope?

Holds the objective lenses and can be turned to increase magnification (A) Signup and view all the answers

What is the role of the stage clips in a microscope?

Hold the slide/specimen in place on the stage (C) Signup and view all the answers

What is the function of the body tube in a microscope?

Holds the objective lenses and ocular lens at proper distance (B) Signup and view all the answers

What is the formula for the resolution of a microscope lens?

$D = \frac{0.61\lambda}{N \times \sin\alpha}$ (D) Signup and view all the answers

How does the wavelength of light affect the resolution of a microscope?

Shorter wavelength leads to greater resolution (B) Signup and view all the answers

What does the resolution of a microscope lens represent?

The minimum distance between two distinguishable objects (A) Signup and view all the answers

What does the fine adjustment knob on a microscope do?

Moves the stage slightly to sharpen the image (A) Signup and view all the answers

How does the wavelength of incident light affect the resolution of a microscope?

Shorter wavelength leads to greater resolution (A) Signup and view all the answers

What is the significance of the angular space between the objective lens and the sample in determining resolution?

It affects the resolution of the microscope (B) Signup and view all the answers

What should you never do when using high magnification lenses (40X, 100X) on a microscope?

Use the coarse adjustment knob (D) Signup and view all the answers

When should you change the lens to a higher magnification one while using a microscope?

If required to observe at a higher magnification (D) Signup and view all the answers

What is the first step when using a microscope to observe a sample on a slide?

Place slide on stage and lock clips (B) Signup and view all the answers

What is the purpose of immersion oil in microscopy?

Prevents light loss due to the bending of light rays as they pass through air (B) Signup and view all the answers

How does the condenser contribute to microscopy?

Collects light on the sample to increase resolution (B) Signup and view all the answers

Why is the oil-immersion lens (100X) narrow?

To prevent most light from missing it (C) Signup and view all the answers

What happens when using oil immersion with a microscope?

Resolution of small objects such as bacteria increases (C) Signup and view all the answers

What is the appropriate cleaning material for a microscope?

Lens cleaning (filter) paper + xylene solution (D) Signup and view all the answers

How does an electron microscope achieve higher resolution than an optical microscope?

Electromagnetic lenses focus a high velocity electron beam with much lower wavelength than visible light (C) Signup and view all the answers

What should be ensured when placing a microscope for use?

It’s on a flat surface (C) Signup and view all the answers

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Study Notes

Microscope: Key Features and Usage

Microscope is an instrument that enlarges the image of minute objects or substances.
The term "microscope" originates from the Greek words "micron" and "skopein," meaning small and to look at, respectively.
Microscopes are broadly classified into light microscopes, which use visible light, and electron microscopes, which use electron beams.
Light microscopes use visible light passed through or reflected from the sample to allow magnified view.
They can distinguish objects separated by 0.2 μM or more.
The common light microscope used in the laboratory is a compound microscope, consisting of ocular and objective lenses.
Magnification is the ratio of the image size to the actual size, determined by multiplying the ocular lens by the objective lens.
Resolution, the ability to distinguish between two close points, depends on the wavelength of light used and the parameters of the microscope lens.
To use a microscope, place the slide on the stage, lock clips, start with lowest magnification, and avoid using the coarse adjustment knob on high magnification lenses.
To increase the resolution with the oil-immersion lens, a drop of immersion oil with the same refractive index as glass is placed between the lens and the glass slide.
Care for a microscope involves cleaning with lens cleaning paper and xylene solution, and ensuring it is on a flat surface.
Electron microscopes use electromagnetic lenses to focus a high-velocity electron beam, providing higher resolution due to the much lower wavelength of the electron beam compared to visible light.

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