3.2) The electron microscope

Question 1

How do electron microscopes work?

Answer 1

A beam of electrons that are focused by electromagnets inside a vacuum environment.

Question 2

What are the two types of microscope?

Answer 2

1. Optical microscope (light)
2. Electron microscope

Question 3

What are the advantages of electron microscopes?

Answer 3

• It has better resolution that optical(light microscopes)

Question 4

What are the disadvantages of electron microscopes?

Answer 4

• The interior of the microscope is a vacuum, so we cannot view living specimens
• The specimen has to be thin and carefully stained
• Can see artifacts(false images)

Question 5

What are the two types of electron microscopes?

Answer 5

1.Transmission Electron Microscope
2. Scanning Electron Microscope

Question 6

How does a transmission electron microscope work?

Answer 6

An electron beam passes through the specimen and produces flat 2D images

Question 7

How does a scanning electron microscope work?

Answer 7

The electron beam does not pass through the specimen, electrons are scattered from the surface of the specimen and detected

Question 8

What are some advantages of the transmission electron microscope (TEM)?

Answer 8

• High resolution

Question 9

What are some disadvantages of the transmission electron microscope (TEM)?

Answer 9

• Specimen has to be thin
• Cannot be used to observe live specimens

Question 10

What are some advantages of the scanning electron microscope (SEM)?

Answer 10

• Produces 3D images
• Specimen doesn’t have to be thin

Question 11

What are some disadvantages of the scanning electron microscope (SEM)?

Answer 11

• Lower resolution
• Specimen has to be coated with a metal (gold) –> can lead to artifacts