question

What part of the microscope is mounted on the nosepiece?

answer

objective lenses

question

Four basic steps in successfully viewing a specimen under the microscope?

answer

setup focusing magnification

question

Depth of field is ______________.

answer

greatest at low power and decreases as magnification increases

question

As magnification increases ____________.

answer

the field diameter decreases

question

Which of the following terms refers to the ability of a lens to clearly distinguish adjacent objects as separate?

answer

Resolution

question

Resolution is defined as

answer

being able to see adjacent objects as separate.

question

What must be done when using a microscope

answer

Carry the microscope with two hands, one on the arm and the other on the base. Completely unwrap the electrical cord before plugging in the microscope. Store the microscope with the cord wrapped neatly around the base, with the lowest power lens in position. Store the microscope with the low-power objective lens in position. Checking the position of the condenser

question

Why should you never clean the microscope with any soft cloth or tissue and water.

answer

The lenses should only be cleaned with lens paper and lens cleaner.

question

Depth of field

answer

the amount (thickness) of a specimen that is in focus

question

Parfocal

answer

lens design that allows specimens to remain near focused at different magnification powers

question

Compound microscope

answer

microscope that uses more than one lens to direct light through a specimen mounted on a glass slide

question

Working distance

answer

distance between objective lens and the upper surface of the slide, with the specimen in focus

question

Field of view

answer

visible area that is seen when looking through the oculars.

question

The ability to distinguish between two objects located close to each other is called ____________.

answer

resolution

question

The _________ is the supportive frame of the microscope that joins the body tube to the base.

answer

arm

question

The _________ is the eyepiece where you place your eyes to observe the specimen.

answer

ocular lens

question

The _______ is a small lens under the stage that narrows the beam of light and directs it through the specimen on the slide.

answer

condenser

question

The body tube is the broad flat portion that supports the microscope. (T/F) (Why / Why Not)

answer

False - the body tube supports the ocular lenses.

question

Upon initial observation of a specimen, it is best to start with the highest magnification lens in place. (T/F) (Why / Why Not)

answer

False - it is easiest to initially focus using the lowest power magnification as a large portion of the specimen will be in the field of view.

question

The ocular lenses are mounted to the nose piece and have variable magnifications. (T/F) (Why / Why Not)

answer

False - the ocular lenses are mounted to the body tube and typically magnify the image ten times (10X).

question

If the field of view is too bright, the light intensity can be lowered by turning the fine adjustment knob. (T/F)

answer

False

question

What are the two ways the brightness or light intensity can be lowered

answer

First, the iris diaphragm creates an aperture that regulates the amount of light passing through the condenser and ultimately the ocular lenses. Second, the amount of light emitted from the light source can be adjusted by turning the illumination intensity control typically located near the on/off switch on a microscope.

question

All of the following are steps in setting up the microscope in order to view a specimen EXCEPT _________.

answer

focusing

question

All of the following are correct steps in focusing on a specimen under the microscope EXCEPT which statement?

answer

Start with a high power objective lens when focusing.

question

In focusing on a specimen under the microscope, you must

answer

When you are ready to change magnification, do not move the adjustment knobs before changing the objective lens. Once the image is clear, use the fine adjustment knob to focus on small details. If two images are visible, slowly move the body tubes closer together until you see with both eyes open, a single circular field of view.

question

All of the following are ways to best control the magnification of the microscope EXCEPT which statement?

answer

To examine part of the specimen at higher magnification, move that part of the specimen off to the side.

question

To best control the magnification of the microscope

answer

Always use low magnification during your initial observation. To examine part of the specimen at higher magnification, move that part of the slide to the center over the aperture before changing to a higher-magnification lens. Use a drop of immersion oil to look at the specimen under the highest magnification.

question

If a student is using the 40X lens, what is the total magnification of the image being viewed?

answer

400X If the 40X objective was being used, the total magnification would be 400X. (10 x 40 = 400).

question

Total magnification is determined by

answer

multiplying the magnification of the ocular lens by that of the objective lens.

question

The ocular lens has a magnification power of

answer

10

question

At higher magnification the light intensity should be decreased so that the image will have good contrast. (T/F) (Why/Why Not)

answer

False - at higher magnifications the amount of light should be increased to adjust the brightness allowing for good contrast and no glare.

question

When preparing a wet-mount it is important to cover the specimen with a cover slip to ensure that the objective lenses remain dry. (T/F) (Why/Why Not)

answer

True - water or other liquids will damage the objective lenses.

question

If a paramecium appears to be moving to the left in the microscopic field of view, which way should you move your slide to keep it in view?

answer

Left The image through the microscopic view is opposite of the real image being emitted. to keep the specimen in the field of view, the mechanical stage should be moved to the left.

question

The virtual image being viewed through the ocular lenses is

answer

inverted and opposite of the real image being emitted into the objective lens

question

If the image through a microscope appears to be moving to the left

answer

it is actually moving right.

question

The in-focus thickness of a specimen viewed under a microscope is called the _____________.

answer

focal plane

question

The focal plane thickness _________ as magnification __________.

answer

decreases; increases

question

The amount of a specimen that is in focus at any given time is called the __________.

answer

Depth of field

question

Field of view

answer

is the entire area that is seen when looking through the ocular lenses.

question

field diameter

answer

distance from either side of the image through the center, which is dependent on magnification. As magnification increases the field diameter decreases.

question

As magnification increases the field diameter

answer

decreases

question

Working distance

answer

amount of space between the upper surface of the glass slide and the lowest part of the objective lens.

question

Parfocal

answer

refers to the ability of the microscope to stay nearly in focus when moving between objective lenses of different magnification.

question

Viewing the slide with the layered colored threads demonstrated that _____.

answer

At higher magnification less of the slide is visible in the field of view The focal plane is thinner at higher magnification Depth of field is greatest at low power Each thread layer comes into focus separately because the specimen is three-dimensional (it has thickness) By moving the fine adjustment knob back and forth, the layers of the specimen will come in and out of focus

question

When using the fine adjustment knob to focus, the lens will move either closer to or farther away from the slide, thus causing the focal plane to move through the specimen layers. (T/F)

answer

True

question

As the magnification __________, the field diameter ___________.

answer

increases; decreases

question

If the field diameter is 8mm and an object occupies one-half of the field, the object is approximately ______wide.

answer

4mm

question

To measure the field diameter what procedures should be taken

answer

Use your low-power measured field diameter to calculate the field diameter for high power. Position the slide so that a vertical line on the paper lines up with the edge of the field. Count the number of millimeters across the field to measure the field diameter.

question

The following are all procedures to measure the field diameter EXCEPT which statement?

answer

Position the slide so that the horizontal line on the paper is on the top of the field.

question

At lower magnification the field diameter is

answer

larger

question

As magnification increases the diameter of the image being viewed

answer

decreases

Exercise 2: Use of the Microscope

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