Lab 3 - The Microscope

1. Click the scanning objective into position above the specimen 2. Use the coarse adjustment knob to move the stage all the way up. 3. Use the fine adjustment knob until the specimen is in focus 4. Adjust the iris diaphragm and/or the light control knob to improve contrast 5. Use the mechanical stage controls to move a given structure to the center of your field of view

Proper focusing technique

Stage

The microscope slide rests on the ________ while being viewed.

Much greater than the working distance for the 100x objective lens

The working distance for a 10x objective lens is...

False

True or false - you should always begin observation of specimens with the oil immersion lens.

450x

What is the total magnification of a specimen viewed with a 10x ocular lens and a 45x objective lens?

lowest

When observing a slide under a microscope, begin focusing with the _____ power objective lens in place

fine adjustment knob

When using the higher power objective lenses, you would use this part of the microscope to focus the specimen.

stage

When you want to study a microscope, you place it on the _______.

Yellow

You are looking at a slide of three crosses threads. Yellow is in the bottom, blue is in the middle, and red is on the top. When you rotate the adjustment knob forward (away from you) on your microscope, the stage rises. You live the adjustment knob to focus on the middle thread. As you rotate the adjustment knob forward, which color thread will come into focus next?

Lowest-power, course

You begin your observations using the _____ lens and the ____ adjustment knob

Prepare another slide and stain with methylene blue

You prepare a wet mount of your own cheek cells and place it under the microscope, but find that high cannot see any detail of the cells. What can you do to make it more visible?

Parafocal

image should remain almost in focus when changing to higher magnifications

total magnification

objective lens x ocular lens

Resolution

Ability of a microscope to distinguish two objects as separate

Decreases

As total magnification increases, the depth of field...

Decreases

As you increase the total magnification of a specimen, the size of field ______.

Decreases

As you increase the total magnification of a specimen, the working distance ______.

Rotate the highest power objective lens into position

Before putting away a microscope in the storage cabinet, you must observe all of the following except

Diameter of field A x Total mag. of field A = Diameter of field B x Total mag. Of field B

Formula for calculating the diameter of an unknown microscope field

Nosepiece

Holds the objectives and can be rotated to change the magnification

Open or close the iris diaphragm

How can you improve the contrast of a specimen?

With special lens paper and cleaner

How do you clean the lenses of your microscope?

Upright, with one hand on its arm and the other hand supporting its base

How to transport a microscope

Field of view

The area visible through the microscope eyepiece

Condenser

concentrates light on the specimen

working distance

distance between the objective and the object being viewed