3.2: The electron microscope Flashcards
Light microscopes have poor resolution as a result of the what?
Light microscopes have poor resolution as a result of the relatively long wavelength of light
Light microscopes have poor resolution as a result of the relatively long wavelength of light.
In the 1930s however, a microscope was developed that used a beam of electrons instead of light.
An electron microscope has 2 main advantages:
1. The electron beam has a what?
The electron beam has a very short wavelength
Light microscopes have poor resolution as a result of the relatively long wavelength of light.
In the 1930s however, a microscope was developed that used a beam of electrons instead of light.
An electron microscope has 2 main advantages:
1. The electron beam has a very short wavelength and the microscope can therefore do what?
The electron beam has a very short wavelength and the microscope can therefore resolve objects well - it has a high resolving power
Light microscopes have poor resolution as a result of the relatively long wavelength of light.
In the 1930s however, a microscope was developed that used a beam of electrons instead of light.
An electron microscope has 2 main advantages:
1. The electron beam has a very short wavelength and the microscope can therefore resolve objects well - it has a high resolving power.
2. As electrons are negatively charged, the beam can be what?
As electrons are negatively charged, the beam can be focused using electromagnets
The best modern electron microscopes can do what?
The best modern electron microscopes can resolve objects that are just 0.1 nm apart
The best modern electron microscopes can resolve objects that are just 0.1 nm apart, how many times better than a light microscope?
The best modern electron microscopes can resolve objects that are just 0.1 nm apart, 2,000 times better than a light microscope
Electrons are what by the molecules in air?
Electrons are: 1. Absorbed Or, 2. Deflected by the molecules in air
The best modern electron microscopes can resolve objects that are just 0.1 nm apart, 2,000 times better than a light microscope.
Because electrons are absorbed, or deflected by the molecules in air, what has to happen in order for it to work effectively?
Electrons are: 1. Absorbed Or, 2. Deflected by the molecules in air, a near-vacuum has to be created within the chamber of an electron microscope in order for it to work effectively
How many types of electron microscopes are there?
There are 2 types of electron microscopes, the:
- Transmission electron microscope (TEM)
- Scanning electron microscope (SEM)
The greater resolving power of an electron microscope compared to a light microscope is due to what?
The greater resolving power of an electron microscope compared to a light microscope is due to the electron beam having a shorter wavelength than light
The transmission electron microscope (TEM) consists of what?
The transmission electron microscope (TEM) consists of an electron gun that produces a beam of electrons
The transmission electron microscope (TEM) consists of an electron gun that produces a beam of electrons that is what?
The transmission electron microscope (TEM) consists of an electron gun that produces a beam of electrons that is focused onto the specimen by a condenser electromagnet
The transmission electron microscope (TEM) consists of an electron gun that produces a beam of electrons that is focused onto the specimen by a condenser electromagnet.
In a transmission electron microscope (TEM), the beam passes through what?
In a transmission electron microscope (TEM), the beam passes through a thin section of the specimen
The transmission electron microscope (TEM) consists of an electron gun that produces a beam of electrons that is focused onto the specimen by a condenser electromagnet.
In a transmission electron microscope (TEM), the beam passes through a thin section of the specimen.
Parts of this specimen do what?
Parts of this specimen:
- Absorb electrons
- Therefore appear dark
The transmission electron microscope (TEM) consists of an electron gun that produces a beam of electrons that is focused onto the specimen by a condenser electromagnet.
In a transmission electron microscope (TEM), the beam passes through a thin section of the specimen.
Parts of this specimen absorb electrons and therefore appear dark.
Other parts of the specimen do what?
Other parts of the specimen:
- Allow the electrons to pass through
- So appear bright
The transmission electron microscope (TEM) consists of an electron gun that produces a beam of electrons that is focused onto the specimen by a condenser electromagnet.
In a transmission electron microscope (TEM), the beam passes through a thin section of the specimen.
Parts of this specimen absorb electrons and therefore appear dark.
Other parts of the specimen allow the electrons to pass through and so appear bright.
An image is produced where?
An image is produced on a screen
The transmission electron microscope (TEM) consists of an electron gun that produces a beam of electrons that is focused onto the specimen by a condenser electromagnet.
In a transmission electron microscope (TEM), the beam passes through a thin section of the specimen.
Parts of this specimen absorb electrons and therefore appear dark.
Other parts of the specimen allow the electrons to pass through and so appear bright.
An image is produced on a screen and this can be what to give what?
An image is produced on a screen and this can be photographed to give a photomicrograph
The transmission electron microscope (TEM) consists of an electron gun that produces a beam of electrons that is focused onto the specimen by a condenser electromagnet.
In a transmission electron microscope (TEM), the beam passes through a thin section of the specimen.
Parts of this specimen absorb electrons and therefore appear dark.
Other parts of the specimen allow the electrons to pass through and so appear bright.
An image is produced on a screen and this can be photographed to give a photomicrograph.
The resolving power of the transmission electron microscope (TEM) is what?
The resolving power of the transmission electron microscope (TEM) is 0.1 nm
The transmission electron microscope (TEM) consists of an electron gun that produces a beam of electrons that is focused onto the specimen by a condenser electromagnet.
The resolving power of the transmission electron microscope (TEM) is 0.1 nm, but this can not always be achieved in practice, because what limit the resolution that can be achieved?
The resolving power of the transmission electron microscope (TEM) is 0.1 nm, but this can not always be achieved in practice, because difficulties preparing the specimen limit the resolution that can be achieved