B - The Microscope and Its Use
When is the Oil Immersion Objective be used?
To view small cells like bacteria
What is an electron microscope?
a binocular that works by passing a concentrated beam of electrons through an almost transparent, ultra-thin section of a specimen. It is magnified using a series of magnets. It can magnify up to 100,000x
What is base lamp and light switch?
light must pass through the specimen in order to view it using a compound light microscope
What is stage with stage clips?
the flat platform where slide specimens are placed
Is it usually more desirable to increase, or decrease, the light when switching to a higher magnification?
Increase
What is the name of the black lever on the microscope that allows you to vary the amount of light passing through the condenser lens?
Iris diaphragm lever
What is the appearance of the letter e when viewed under the microscope?
It appears larger
What is magnifying power?
It indicates how many times larger an object appears compared to its actual size
What is the binocular dissecting microscope?
It is designed to examine any type of specimen at low magnifying powers. It has a magnifying power of 5x. It is used to examine a pine cone or grass
If the letter e slide is moved to the right, in what direction does it appear to move in the field of view through the microscope?
It moves to the left
What is a wet mount used for?
to examine a living organism or tissue
What is focusing knob?
used to raise and lower the objective lenses
The property of a lens to produce a sharp distinct image is called what?
Resolving Power
What is a compound light microscope?
A binocular that works by passing a beam of light through a thin specimen. It can magnify up to 2,000x
What is an objective lens?
A compound light microscope consists of an ocular lens and an objective lens to increase the magnifying power. This is held by a revolving nosepiece. This is the lens closest to the specimen
How do you estimate the size of an object in the field of view?
By comparing it to the diameter of that field. The lens are in micrometers
What can you see using a transmission electron microscope?
.1- 1 x 10-7 like protein helix
What can you see using a useful range of optical microscope?
.1cm-.0001cm - human red blood cell & bacterium
You are looking at a pond creature under the microscope. It covers 1/2 of the field of view. The diameter if the field of view is 2,000 micrometers. What is the aprox length of the pond creature?
1,000 mcrometers
What does the label on a slide identify?
1. The organism or tissue that is one the slide 2. how the specimen was sectioned 3. the dye used to stain the specimen
What are the magnifications of the low, high-dry & oil immersion lens?
10x, 40x, 100x
What can you see with a scanning electron microscope?
1cm to 1 x 10-6 like plasma membrane
What can you see with a human eye?
1cm-.01cm - frog's egg & amoeba
Which objective lens is the closes to the specimen when in focus?
Blue, high power, 40x, .4mm diameter of field, 400x total magnification
Which objective lens should be used first to examine a specimen?
Red, scanning
Which objective lens transmit the most amount of light and has the greatest depth of focus?
Red, scanning, 4x, 4mm diameter of field, 40x total magnification
How do you distinguish an air bubble on a wet mount?
The bubbles usually appear as perfect circles with very dark borders.
Which lens in the compound light microscope has nothing to do with magnification?
The condenser lens, it focuses the beam of light from the lamp onto the specimen
What is diameter of the field of view?
The distance from one side of the field to the other. The greater the magnification, the smaller the diameter of the field of view
What is a depth of focus field?
The distance that is in focus at any one time. The greater the magnification the thinner is the layer that is in focus at any one time. The amount of view you see through a specimen. as the magnification increases the depth of focus decreases.
Why is it necessary to center the object you wish to look at before switching to a higher magnification?
The greater the magnification, the thinner the layer that is in focus at any one time. This is way there is more in focus at one time
What is field of view?
The illuminated circular area that you see when you look into the microscope
What is the ocular lens?
The lens that you look into. It has a magnifying power of 10x.
If the letter e slide is moved away from you, in what direction does it appear to move in the field of view through the microscope?
Towards you
What is low power?
yellow 10x, 2mm diameter of field, 100x total magnification
