CB1A Microscopes Flashcards
How can the magnification of an image be calculated
Magnification = size of image
—————–
size of specimen
How can the total magnification of an image be calculated from lens powers
Total magnification = eyepiece lens magnification x objective lens magnification
How do you convert from m to mm
x1000
How do you convert from m to nm
x 1,000,000,000
How do you convert from m to pm
x 10 to power of 12
How do you convert from m to μm
x 1,000,000
How do you convert from nm to m
Divide by 1,000,000,000
How does a light microscope work
Passes a beam of light through a specimen which travels through the eyepiece lens allowing the specimen to be observed
How does an electron microscope work
It uses a beam of electrons which are focused using magnets. The electrons hit a fluorescent screen which emits visible light producing an image
How have electron microscopes enabled scientists to develop their understanding of cells
Allow small sub-celluar structures (e.g mitochondria and ribosomes) to be observed in detail
Enable scientists to develop more accurate explanations about how cell structure relates to function
Instead of Light, beams of what pass through a specimen to build up an image
Electrons
What are the advantages of light microscope (4)
Inexpensive
Easy to use
Portable
Observe both dead and living specimens
What are the disadvantages of electron microscopes (4)
Expensive
Large so less portable
Require training to use
Only dead specimens can be observed
What is magnification
The number of times bigger an image appears compared to the size of the specimen
What is resolution
The smallest distance between two objects that can be distinguished
