CH2- quiz 1 (1.2)

4x objective lens

- located directly above the specimen . -Lowest objective lens on our microscopes -Starting lens - Can be focused using coarse adjustment knob followed by the fine adjustment knob

40x objective lens

-High power lens -Can only be focused with fine adjustment knob!!NEVER use coarse adjustment knob

microscope resolution

-The ability to distinguish two objects that are close together as being two separate objects, rather than just one. -Increases fine detail.

10x objective lens

-magnifies 10x -can be focused using the coarse adjustment knob followed by the fine adjustment knob

all of the following statements about the care of the microscope is true

A Carry the microscope with both hands: one on the base, another on the arm B Unplug the microscope by firmly pulling the plug (not the cord) C Use grit-free lens paper to clean all lenses

Which of the following can you use to adjust the light conditions on your specimen?

A Iris diaphragm

all of the following statements is true?

A The most common magnification of the ocular is 10X B The coarse adjustment knob is the larger knob on either side of the microscope D A microscope is an instrument that allows us to observe very small objects

As you increase the magnification, the specimen you are viewing appears larger However, you are looking at a smaller portion of the specimen In other words, as you increase the magnification, the ____________________ gets smaller

A field of view

Binocular Eyepiece/ocular

A microscope head with two eyepiece lenses, magnifies images 10 times larger than actual size

lens

A piece of glass that transmits light (allows light to pass through it) & refracts light (bends light)

Relationship between magnification & light intensity

As magnification increases, light intensity decreases. This means that the 10x objective is brighter than the 40x objective.

Relationship between magnification & field of view

As magnification increases, the field of view decreases! (You see less of the specimen but in more detail)

Relationship between magnification & working distance

As magnification increases, the working distance decreases (there is less space between the lens and the slide).

You should use the __________________ to focus when you are using the 40X objective

B fine focus knob

Base

Bottom of the microscope -Supports the microscope -Used to carry the microscope

If the field of view is 0.45 mm in diameter and three cells can fit lengthwise across the field of view, how long is one cell?

C 150 µm microns

stage

Flat platform that supports/holds the slide being observed

If your specimen appears too far to the right of center, which direction do you need to push the slide or specimen for it to become centered?

If the specimen appears to the right of center, when viewed through the scope, it needs to be pushed to the actual right across the stage. This will make it appear to move left across the field of view when looking through the microscope, bringing it closer to center

Microscope Misconceptions

In typical microscopes, the image that you see through the eyepieces is actually inverted and backwards relative to how that object is oriented on the slide. This is due to the mirrors that direct the light coming off the image to your eyes. So, in a typical microscope: up appears down and right appears left!

Diaphragm

Located under the stage -Regulates the amount of light that enters the stage

Were you able to get both hairs perfectly into focus at the same time at high power? Why?

No. as you focus on 1 of the hairs, the other goes out of focus. This is because DOF declines as magnification increases

light source

Projects light upwards through the diaphragm, the specimen, and the lenses

mirror

Reflects light up through the stage & on to the specimen

arm

Supports the body tube & lensesIt is used to carry the microscope

field of view

The area visible through the microscope eyepiece/ocular

working distance

The distance between: - the tip of the objective and the slide. - the coverslip on the slide and the lower end of the objective lense. -(Note that the greater the magnification of the objective, the smaller the working distance. ) -decreases as magnification increases.((there is less space between the lens and the slide)

What happens to the field of view when you increase the magnification?

The field of view starts to decrease. -when a specimen is magnified, the microscope is zooming in on it and, consequently, seeing less of it (but in greater detail).

specimen

The object which you are viewing under the microscope

total magnification

The overall magnification when more than one lens is used -ocular lens x(times) objective lens

depth of field

The thickness of a specimen that can be seen in focus at one time --decreases as the magnification increases

How do you find the low power field of view diameter?

Use a thin, clear metric ruler and DIRECTLY measure the FOV by focusing the ruler under the low power objective.

compound microscope

Uses light and two lenses to create an enlarged image(This is the type of microscope in our classroom)

How do you find the high power field of view?

You cannot directly measure the high power FOV. You must CALCULATE it by using the low power to high power magnification ratio.

parfocal microscope

allows for specimens to remain in focus when changing between low and power magnification (use only fine focus knob to sharpen focus)

microscope

an optical instrument used for viewing very small objects, such as mineral samples or animal or plant cells, typically magnified several hundred times.

Why must you use the formula for determining the field size at higher magnifications (why can't you use the ruler, like you did at low magnification)?

at high magnification, the field of view becomes so small that the lines of the ruler will no longer be visible).

When you examined the hairs at higher magnification, what were you able to see that you could not see at low power?

at higher magnification "black" hair will appear as dark brown. Striations are sometimes visible. Split ends and aberrations in the hair are sometimes visible

nosepiece (turret)

holds the HIGH and LOW power objective lenses, can be rotated to change magnification

stage clips

holds the slide in place on the stage

What can you do if you want your specimen to appear right side up?

in order to make the specimen appear right side up, when viewed under the microscope, it can be placed upside down on the stage

body tube

maintains the proper distance between the ocular lense/eyepiece and the objective lenses

Coarse adjustment knob/focus

moves stage up and down for focusing. -Larger of the focusing knobs -can only be used with the low 4x and 10x objective lenses

fine adjustment knob

moves the stage slightly to sharpen or "fine" tune focus under 4x, 10x and 40x -the only focusing knob that can be used with the high power lens.

A specimen in focus at one magnification will be in focus at all magnifications, with only minor adjustments needed with the fine focus This is because the microscope is __________

parfocal

Average cell size(Formula)

the diameter of the field of view DIVIDED by the number of cells that fit across the field of view

What happens to the orientation of a specimen when viewed under the microscope?

the image as viewed under the microscope appears upside down compared with its actual orientation

*** When you are using a 10X ocular and the 10X objective,

the image you see through the ocular is magnified 100X