Biology 2.1.1: Microscopes Flashcards
1
Q
Magnification definition
A
how many times larger the image is compared to the object
2
Q
Resolution definition
A
The minimum distance between two objects in which they can still be viewed as separate
3
Q
How is the resolution in a optical microscope determined?
A
The resolution is determined by the wavelength of light
4
Q
How can the resolution detained in electron microscopes?
A
The wavelength of the beam of electrons.
5
Q
Optical (light) microscopes
A
- beam of light is condensed to create an image
- poorer resolution due to the large wavelength of light
- lower magnification
- colour images
- can view living samples
6
Q
Electron microscopes
A
- beam of electrons is condensed to create the image ( electromagnets are used to condense the beam)
- high resolving power as electrons have a short wavelength
- higher magnification
- black + white images
- sample must be in a vacuum (no living things)
- electrons are absorbed by air
7
Q
Transmission electron microscope (TEM)
A
- extremely thin specimen are stained + placed in a vacuum
- electron gun produces a beam of electrons that pass through the specimen (some parts absorb electrons and appear dark)
- image is produced in 2D + shows detailed internal structure
8
Q
Scanning electron microscope (SEM)
A
- specimens do not need to be thin (electrons are not transmitting)
- electrons beam onto the surface + scatter in different ways depending on the contours resulting in 3D images
9
Q
What are the units of microscopy?
A
M, cm, mm, um, nm
10
Q
Magnification calculation
A
Magnification = magnifying power of the objective lens x magnifying power of the eyepiece lens
