Microscopes Flashcards
Compound light microscope
A microscope with a light and glass lenses used to magnify objects. (Compound means more than one type of lens.)
Magnification for compound microscope
Eyepiece=10x, low/scanning objective lens=4x, medium objective lens=10x, high objective lens=40x. Up to 2000x.
How do you find overall magnification for a compound light microscope?
For overall magnification, multiply eyepiece magnification by chosen lens. Ex: If you use low/scanning objective lens at 4x, then overall magnification is 40x.
Resolution
The quality or clarity of an image. You want the highest resolution.
What does resolution depend on?
Angular aperture (which we don’t use in PB bio), refractive index (medium/substance light travels through: air or oil), and wavelength of light (shorter wavelength, like violet or blue, gives greater resolution).
Making Wet mounts
Place one drop of water on the center of the slide. Place specimen on top. Hold coverslip @ 45 angle above water with one edge resting on the slide. Slowly lower to prevent air bubbles.
Air bubbles
They are round and have dark edges under the microscope.
Why do you use coverslips for wet mounts?
They protect lens from water, keep specimen in place, and protect the specimen.
Field of view
How much of the object you can see.
Which lens has the greatest field of view?
The scanning/low objective lens.
Stains
Artificial color to make transparent images easier to see.
Scanning electron microscope (SEM)
Scans specimen’s surface. Electron beams are used to magnify objects instead of using light. Magnetic lenses and electrons are used to magnify objects up to 250,000x. Metal coating is used on the specimen so that the magnetic lenses will work.
Electron microscope (SEM and TEM)
Electron beams are used to magnify objects instead of using light.
How much do SEMs cost? What kind of images do they produce?
$30,000-$100,000. The image is 3D and black and white unless color is added later.
Transmission electron microscope (TEM)
Transmits electrons through a thin slice of the specimen. Electron beams are used to magnify objects instead of using light. Takes up a whole room. Metal coating on specimen because of magnetic lenses.
What does a TEM cost? How much can it magnify an object? What is one thing it can look at and what kind of image is produced?
Costs $100,000-$200,000. Up to 2,000,000x for magnification. 2D black and white image unless computer adds color. Can look at viruses.
Microtome
A diamond knife for cutting thin slices.
Centrifuge
Spins substances like blood to either mix or separate them; it depends on the substance.
Cell culture
Growing cells in a lab.
Nosepiece
Holds the objective lenses above the stage and rotates so that all lenses may be used.
Diaphragm
Adjusts the amount of light passing through the slide and into the lens.
Base and arm
Base supports the microscope; arm supports the body above the stage.
Stage clip
Holds a slide in place on the stage.
Body
Separates the lens in the eyepiece from the objective lenses below.
Stage
Supports the object being viewed.
Light source
Illuminates specimen being viewed.
Coarse adjustment
Used to focus the image of an object when it is viewed through the scanning and low-power lenses.
Fine adjustment
Used to focus when using the high power lens.
