Types of electron microscope

- Use electromagnets to focus a beam of electrons, which is then transmitted through the specimen. 

- Denser parts of he sepcimen absorb more electrons, which makes them look darker on the image you end up with. 

- TEMs are good as they give high resolution images, so you can use them to look at smaller objects. 

- But you've got to veiw the specimen in a vacuum so they're no good for looking at living organisms. 

- They can also only be used on thin specimens. 

- Scan a beam of electrons across the specimen, which knocks off electrons from the specimen, which are gathered in a cathode ray tube to form an image. 

- the images you end up with show the surface of the specimen and they can be 3-D. 

- SEMs are good as they can be used on thick specimens, but they give lower resolution images than TEMs and still can't be used on living organisms. 

TEMs:

Ads- Give high resolution images, so shows small objects

Disads- Can only be used on thin specimens. 

            - Can only be used on non-living specimens

SEMs:

Ads- Can be used on thick specimens. 

       - Can be 3D

Disads- Give lower resolution than TEMs. 

            - Can only be used on non-living specimens.