6457720
Description
Flashcards by Bethany Westwood, updated more than 1 year ago
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Created by Bethany Westwood
over 9 years ago
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| Question | Answer |
| What is magnification? | How many times bigger an image is than the specimen |
| What is resolution? | Determines the amount of detail Ability to see two different objects seperatey |
| What is resolution limited by? | The diffraction of light |
| Why are two objects sometimes seen as one? (Poor resolution) | 2 objects too close Light reflected from each can overlap due to diffraction Cannot see the 2 separate objects |
| What is the resolution in an optical microscope? | Half a wavelength |
| Why do electron microscopes have a better resolution? | The use beams of electrons Electrons have a much shorter wavelength Wavelengths still overlap but because the wavelength is smaller, items can be closer before the wavelengths overlap |
| What is the formula for magnification? | Magnification = Image size/actual size |
| What is the magnification of an electron microscope? | x500,000 |
| What does the magnification of an electron microscope allow? | You can see deeper into the cells ultrastructure |
| What happens in a transmission electron microscope (TEM)? | Beam of electrons transmitted through specimen Focused to create an image |
| What happens in a scanning electron microscope (SEM)? | Beam of electrons sent across surface of specimen Reflected electrons collected 3D image produced |
| What is point illumination? | Moves a single spot of light across a specimen |
| What does point illumination do? | Causes fluorescence from components labelled with a "dye" |
| What is fluorescence ? | Absorption and re-radiation of light |
| How does laser scanning confocal microscopy work? | Emitted light is filtered through a pin hole aperture Only light very close to focal plane is detected 2D image produced |
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