Ch 3 - Microscopy

Question 1

Magnification

Answer 1

The amount that the image of an object is enlarged

Question 2

Resolving power

Answer 2

The extent to which an object detail in an image is preserved during the magnifying process

Question 3

Contrast

Answer 3

The degree to which an image details stand out against their background

Question 4

How to carry a microscope

Answer 4

Grasp the arm with dominant hand and support the base with other hand, keeping upright

Question 5

How to clean oculars

Answer 5

A piece of lens paper moistened with lens-cleaning solution

Question 6

Parts of microscope

Answer 6

1. Light source
2. Condenser
3. Stage
4. Focusing Knobs
5. Objectives

Question 7

What does the condenser do?

Answer 7

The condenser lens and iris diaphragm focus the light source so the specimen is evenly illuminated

Question 8

What are the two kinds of focusing knobs?

Answer 8

Coarse-focus and fine-focus

Question 9

What are the two magnifying lenses?

Answer 9

The objective and the ocular

Question 10

Parfocal

Answer 10

When objective has been focused, you can rotate between objectives and it will still be in focus

Question 11

Paracentral

Answer 11

Center of the field of view remains about the same for each objective

Question 12

Field of view

Answer 12

The circle of light you see when looking into the microscope

Question 13

Working distance

Answer 13

The space between the objective lens and the slide

Question 14

What is the basic unit of measurement at the light-microscope level?

Answer 14

Micrometer (um)

1000 um = 1 mm
1 um = 0.001 mm

Question 15

What are Dissecting Microscopes useful for?

Answer 15

In viewing larger specimens and manipulating the specimen

Question 16

What do phase-contrast and Nomarski process do? & how are they used?

Answer 16

Convert phase differences in light to differences in contrast

Useful in the observation of low-contrast specimens (often living)

Question 17

What do Transmission electron microscope do? & how are they useful?

Answer 17

Increase resolving power by using electrons in a vacuum and magnetic lenses instead of light and glass lenses

Allows greater specimen magnification (usually dead materials)

Question 18

What does the scanning electron microscope do? & how is it useful?

Answer 18

Forms a TV-like picture from a secondary electron signal, which is emitted from surface points excites by a thin beam of electrons drawn across

Can see the fine structure of surfaces (usually dead specimen)