Microscopy Flashcards
Object
Real object or sample being looked at
Image
Image seen when looking down the microscope
Magnification
How many times larger the image is than the object
Magnification equation
Magnification = Image size/Object size
Resolution
The shortest distance between two objects that can be distinguished
Order of magnitude
A power to the base of 10 (standard form) used to quantify and compare size
How does a light microscope work
Passes a beam of light through a specimen which travels through the eyepiece of a lens, allowing the specimen to be observed
Advantages of a light microscope
-Inexpensive
-Easy to use
-Portable
-Can observe both dead and live specimens
Disadvantages of a light microscope
Limited resolution
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
What are the two types of electron microscopes
Transmission electron microscope
(TEM)
Scanning electron microscope (SEM)
Advantages of electron microscopes
-Greater magnification and resolution
-Allows small sub-cellular structures to be observed in detail
Disadvantages of electron microscopes
-Expensive
-Large so less potable
-Requires training to use
-Only dead specimens can be observed
Maximum magnification of light microscopes
X2000
Maximum magnification of of electron microscopes
X2,000,000
Resolving power/resolution of light microscope
200nm
Resolving power/resolution of electron microscope
10nm(SEM)
0.2nm(TEM)
Magnification of a light microscope =
Magnification of the eyepiece lens X magnification of the objective lens
Size of an object=
Size of image/Magnification
