Lab Exam 2: Microscopy

Question 1

Difference between the course focus knob and the fine focus knob?

Answer 1

The course moves the stage faster while the fine moves the stage more slowly.

Question 2

How to calculate total magnification?

Answer 2

Ocular x objective

Question 3

Working distance

Answer 3

distance between the objective lens and the slide (on the stage)

Question 4

Does the working distance get smaller or larger as your increase magnification?

Answer 4

The distance gets smaller.

Question 5

Condenser

Answer 5

located above the light source and under the sample in an upright microscope, and above the stage and below the light source in an inverted microscope. They act to gather light from the microscope’s light source and concentrate it into a cone of light that illuminates the specimen.

Question 6

Filed of View

Answer 6

This is the area of the slide you see as you look through the microscope.

Question 7

Relationship between filed of view and magnification?

Answer 7

greater the magnification, smaller the field of view.

Question 8

How to estimate size?

Answer 8

Use the diameter of the field of view.

40X (scanning): 5 mm
100X (low power): 2 mm
400X (high-dry lens): 0.5mm (500 μm)
1000X (oil immersion): 0.2 mm (200 μm)

Question 9

Typical microscope lens powers?

Answer 9

4x, 10x, 40x, and 100x

Question 10

Parfocal

Answer 10

When microscopes are “almost” in focus when moving from one objective to another.

Question 11

Resolution

Answer 11

the ability of a microscope to distinguish details of a specimen or sample. In other words, the minimum distance between 2 distinct points of a specimen where they can still be seen by the observer or microscope camera as separate entities

Question 12

Which objective lens has the largest working distance?

Answer 12

4x

Question 13

Which objective has the smallest working distance?

Answer 13

100

Question 14

What special precautions must be taken when using the oil immersion (100x) objective?

Answer 14

Not to go back to the 40x as it will damage the lens.

Question 15

Describe the proper way to store a microscope in terms of stage position, light intensity knob, and objective position.

Answer 15

Stage in lowest position, light off, and objective on the lowest lens.

Question 16

Does it matter which objective is clicked into position when you store your microscope? If so, why? if not why not? How will you store your microscope away?

Answer 16

Yes, lowest should be in position as it is the shortest to avoid the lens scratching or hitting the stage.

Question 17

How does oil help the viewing of an object at 100x objective?

Answer 17

It forms a continuous lens system that limits the loss of light . Improves resolution.

Question 18

A student chicks the oil immersion lens into position after using he high dry by first lowering the stage a little to avoid damaging the lens or slide. Critique his technique using proper terms.

Answer 18

You should not lower the stage when switching to 100x as it will cause the specimen to be out of focus.