B1.1.4 - Electron Microscopy

Question 1

What is resolution?

Answer 1

The resolution of a microscope is defined as the smallest distance that can be seen as separate entities.

Question 2

What is different from the light microscope to the electron microscopes

Answer 2

Electron microscopes use electron rather than light to produce an image. The greater resolution is achieved by using high-energy electrons as the ‘light source’

Question 3

What are the two types of electron microscope?

Answer 3

Transmission electron microscopes and Sampling electron microscopes

Question 4

What are the features of a TEM?

Answer 4

TEMs produce the most magnified images, producing them up to 1x10nm (1x10-10m). How it works is a beam of electrons passes through s very thin slice of the sample. The beam is focused to produce an image

Question 5

What are the features of an SEM?

Answer 5

They produce a 3D image of a surface. They send a beam of electrons across the surface of a specimen. The reflected electrons are gathered to produce an image.

Question 6

What are the pros and cons of light microscopes?

Answer 6

Pros - Cheap to buy and operate, small and portable, simple to prepare a sample, natural colour oh sample is seen unless staining is used and specimens can be live or dead

Cons - Resolution only unto 0.2 micrometers (2x10-7m)

Question 7

Pros and cons of Electron microscopes

Answer 7

Pros - Resolution up to 0.1 nanometer (1x10-10m), image can be in 3D

Cons- Expensive to buy and operate, large and difficult to move, sample preparation is complex, specimens must be dead and the images produced are black and white