Types of microscopes

Question 1

What are the two types of electron microscopes

Answer 1

TEM and SEM

Question 2

TEM or SEM which microscope has the higher resolving power?

Answer 2

TEM has a higher resolving power than SEM

Question 3

What are limitations of a TEM microscope?

Answer 3

• You have to be highly skilled to prepare the specimen as it has to be very thin therefore is easy to have artefacts
• Complex staining process which may result in artefacts . The staining process is required even though the image is not in colour
• the finished image is not in colour
• organism you are studying under the TEM has to be dead as the microscope contains a vacuum

Question 4

What is meant by resolution

Answer 4

The minimum distance apart that two objects can be in order for them to appear as separate items. Is also how clear the image is and how precise is it.

Question 5

What is meant by magnification

Answer 5

How many times bigger the image is when compared to the object

Question 6

1. In a SEM are the organisms dead or alive

2. does SEM use a vacuum

Answer 6

1. The organisms can be dead or alive

2. No

Question 7

Which microscopes SEM or TEM are able to use thicker specimens and why

Answer 7

SEM as the electrons do not have to penetrate through the object

Question 8

How does a TEM work

Answer 8

Step 1: the specimen is impregnated with metal
Step 2: A beam of electrons are passed through the specimen and these elections pass through the specimen which are then detected on a fluorescent screen on which the image is displayed.
Thin sections of the specimen are needed for TEM as the electrons have to pass through the specimen for the image to be produced.
TEM is the is the most common form of electron microscope and it has the best resolution

Question 9

How does a SEM work

Answer 9

Step 1: Coat the specimen in a very thin layer of metal, cold or copper
Step 2: A beam of electrons are fired at the specimen. Due to the specimen being coated in a very thin layer of metal the electrons are deflected.
Step 3: The electrons are deflected onto a scanner which picks up the shape of the specimen according to where the electrons bounce off and hit the scanner which therefore will the pick up the shape of the specimen.
The image of the specimen will be 3D but not in colour

Question 10

1. Does SEM produce a black white image or a colour image

2. Does the SEM produce a image in 3D or in 2D

Answer 10

1. SEM produces a image in black and white

2. SEM produces a 3D image

Question 11

Do both images produced by TEM and SEM have to use false colour to produce an image in colour

Answer 11

Yes they do

Question 12

1. What does SEM stand for

2. What does TEM stand for

Answer 12

1. Transmission electron microscope

2. Scanning electron microscope