Topic 2.1 (microscopy) Flashcards
How do you calculate image size?
Image size= actual size x magnification
What is resolution?
The smallest distance apart where two objects are seen as separate
What are the two types of electron microscope?
Transmission and scanning
Which electron microscope requires a metal coating of the sample?
Scanning
What is magnification?
How much bigger the image size is compared to the object size
What is contrast?
The difference between the lightest and darkest parts of an image
What is differential staining?
Applying pigments to specimens to increase contrast. Pigments are selectively absorbed by different substances
Eg iodine: used for plant cells. It turns starch black, leaves the rest orange
Magnification calculation?
Mag= image size/ actual size
General microscope method?
- take a sample and place on side
- stain sample with (eg) iodine or methyl blue
-place on cover
-coarse focus dial to completely lower platform
-start on lowest mag
-turn on light
-put slide on platform
-coarse focus and then fine focus to find specimen
-increase to desired mag and fine focus again
What is a graticule?
A unit-less scale used to measure specimen
Why don’t graticules have units
Because the mag changes the scale/length
How do you get from a mm to a nm?
x by 1,000,000 (a million)
How do you get from a mm to a μm?
x by 1000
Which electron microscope has the highest magnification?
Transmission
Which electron microscope has a higher resolution?
Transmission
