Lab Exam 2: Microscopy Flashcards
Difference between the course focus knob and the fine focus knob?
The course moves the stage faster while the fine moves the stage more slowly.
How to calculate total magnification?
Ocular x objective
Working distance
distance between the objective lens and the slide (on the stage)
Does the working distance get smaller or larger as your increase magnification?
The distance gets smaller.
Condenser
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.
Filed of View
This is the area of the slide you see as you look through the microscope.
Relationship between filed of view and magnification?
greater the magnification, smaller the field of view.
How to estimate size?
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)
Typical microscope lens powers?
4x, 10x, 40x, and 100x
Parfocal
When microscopes are “almost” in focus when moving from one objective to another.
Resolution
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
Which objective lens has the largest working distance?
4x
Which objective has the smallest working distance?
100
What special precautions must be taken when using the oil immersion (100x) objective?
Not to go back to the 40x as it will damage the lens.
Describe the proper way to store a microscope in terms of stage position, light intensity knob, and objective position.
Stage in lowest position, light off, and objective on the lowest lens.
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?
Yes, lowest should be in position as it is the shortest to avoid the lens scratching or hitting the stage.
How does oil help the viewing of an object at 100x objective?
It forms a continuous lens system that limits the loss of light . Improves resolution.
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.
You should not lower the stage when switching to 100x as it will cause the specimen to be out of focus.
