Types of microscopes Flashcards

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1
Q

What are the two types of electron microscopes

A

TEM and SEM

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2
Q

TEM or SEM which microscope has the higher resolving power?

A

TEM has a higher resolving power than SEM

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3
Q

What are limitations of a TEM microscope?

A
  • 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
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4
Q

What is meant by resolution

A

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.

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5
Q

What is meant by magnification

A

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

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6
Q
  1. In a SEM are the organisms dead or alive

2. does SEM use a vacuum

A
  1. The organisms can be dead or alive

2. No

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7
Q

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

A

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

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8
Q

How does a TEM work

A

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

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9
Q

How does a SEM work

A

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

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10
Q
  1. Does SEM produce a black white image or a colour image

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

A
  1. SEM produces a image in black and white

2. SEM produces a 3D image

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11
Q

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

A

Yes they do

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12
Q
  1. What does SEM stand for

2. What does TEM stand for

A
  1. Transmission electron microscope

2. Scanning electron microscope

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