3.2: The electron microscope

Question 1

Why do light microscopes have poor resolution

Answer 1

Due to a long wavelength of light

Question 2

Why are electron microscopes more accurate

Answer 2

Because they used beams of electrons rather than light

Question 3

Advantages of using beams of electrons

Answer 3

1. Electron beam has a very short wave length and the microscope has a high resolution
2. Electrons are negative, therefore electromagnets can be used to focus to the beam

Question 4

What are the two types of electron microscope

Answer 4

1. Scanning Electron Microscope (SEM)

2. Transmission Electron Microscope (TEM)

Question 5

What does a transmission electron microscope produce

Answer 5

A Photomicrogram

Question 6

Why can the resolving power of the TEM not always be achieved

Answer 6

1. Difficulties preparing the specimen limit the resolution that can be achieved
2. A higher energy electron beam is required and this may destroy the specimen

Question 7

SEM vs TEM

Answer 7

TEM

• Higher resolution

SEM

• No need to be thin
• 3D, rather than 2D then slowly produce 3D with TEM