Microscopes

Resolution

The smallest distance that 2 objects can be apart while still appearing as 2 objects

Label the parts of the microscope

Optical vs Electron Microscope

Electron Microscope

• Uses magnets to focus a beam of electrons to either pass through or bounce off the surface of a specimen

• Have a high resolving power because the wavelength of an electron beam is shorter than that of light

• Transmission electron microscopes: the electrons pass through the specimen

• Scanning electron microscope: the electrons bounce off the surface of the specimen

Transmission Electron Microscope (TEM)

• 2D images formed

• Detailed organelles are visible

• Beam of electrons is passed through a very thin specimen

• Electrons pass easily through less dense areas and appear dark whilst electrons pass less easily through more dense areas and appear white

• Resolving power of around 0.1nm

• Magnification of x500,000

• Takes place in a vacuum

Scanning Electron Microscopy (SEM)

• A beam of electrons are bounced off the surface of the specimen

• 3D image is formed

• Allows us to see the shape of whole cells

• Has a slightly lower resolution than TEM of around 20nm

• Lower magnification of x100,000

Electron Microscope: advantages and disadvantages

Eyepiece graticule equation

Magnification Equation