p1 microscopy Flashcards
what are the two types of microscopes
light and electron microscopes
describe a light microscope
(include how far their magnification is)
Light microscopes are used to study living cells and for regular use when relatively low magnification. Light microscopes have a magnification power of up to x2000. They use the beams of light and lenses in order to magnify a living object to create an image. They are cheap and portable and can be used to see cells and large organelles, or sub-cellular structures, such as nuclei.
describe an electron microscope
Electron microscopes cannot be used to view living cells, they use beams of electrons to make a magnified image. They have the magnifying power of around x2,000,0000. Electron microscopes also have a higher resolution.
what are the (4) main differences between light/electron microscopes
include price, weight, resolution/magnification.
1) Light microscopes can be used to view living cells, while electron microscopes cannot.
2) Light microscopes are cheaper and more portable than electron microscopes.
3) Light microscopes use beams of lights while elctron microscopes use electrons.
4) Electron microscopes have a higher resolution and magnification than light microscopes
what is the formula for magnification
image size/real size
method for using a light microscope
6 steps
rotate, focus, place the slide, focus, record, re-focus
1) Rotate the objective lenses so that the low power, eg ×10, is in line with the stage.
2) Turn the coarse focus so that the stage is as close to the objective lens as possible. You should not look through the microscope to do this.
3)Place the microscope slide – either one you have prepared, or a permanent slide – on the stage. Line it up so that the specimen – if you can see it – is in the centre of the stage, where the light passes through.
4)Focus the slide towards you by turning the coarse focus adjustment
5)Draw a low power image or record a digital image of what you see. Then, rotate the objectives so that the high power objective, eg ×40, is in line with the stage
6)Bring the slide back into focus using the fine focus adjustment. If you do not succeed, go back to low power and re-focus, then try again.
what are the risks when using a light microscope
1) Care must be taken when looking down the microscope if the illumination is too bright.
2) Care must be taken when using microscope stains.
3)Care must be taken when handling coverslips and microscope slides.
three things to remember when drawing cells observed through a light microscope
1) use a pencil
2) label the main structures
3) include the magnification used
