Magnification

Question 1

What do you need to do to see organelles in cells

Answer 1

You need to stain the cells

Question 2

How does a light microscope work

Answer 2

A specimen is placed in a beam of light
The beam passes through a specimen and then through a series of lenses magnifying the image

Question 3

In order for light to pass through what does the specimen need to be

Answer 3

The specimen needs to be thin and transparent

Question 4

What are the 4 different slide types

Answer 4

Dry mount, Wet mount, Squash slides, Smear slides

Question 5

What is dry mount

Answer 5

Dry mount - solid specimens are cut into very thin slices with a sharp blade (sectioning). The specimen is placed in the centre of the slide and a cover slip is placed on top.

Question 6

What is wet mount

Answer 6

Specimens are suspended in a liquid such as water or an immersion oil. It is put on a slide and a cover slip is placed on from an angle.

Question 7

What is a squash slide

Answer 7

A wet mount is prepared, and a lens tissue is used to press down on the cover slip.

Question 8

What is a smear slide

Answer 8

The edge if a slide is used to smear the sample creating a thin even coating on another slide.

Question 9

What does the eyepiece lens do

Answer 9

Magnifies and focuses the image from the objective lens onto the eye

Question 10

What does the objective lens do

Answer 10

Collects light passing through the specimen and produces a magnified image

Question 11

What is a condenser lens

Answer 11

Focuses the light onto the specimen between the cover slip and slide

Question 12

What is a condenser iris diaphragm

Answer 12

Closed slightly to produce a narrow beam of light

Question 13

What is the typical power of objective lenses

Answer 13

4x, 10x, 40x

Question 14

What is low power

Answer 14

The lowest power objective lens

Question 15

What is low power

Answer 15

The lowest power objective lens

Question 16

Magnification definition

Answer 16

A measure of how much the image is enlarged relative to the specimen size

Question 17

Resolution definition

Answer 17

the ability to distinguish between 2 points

Question 18

What is the formula for maximum resolution

Answer 18

1/2 x wavelength

Question 19

What is magnification

Answer 19

Size of image/size of object

Question 20

What is an electron microscope

Answer 20

Uses a beam of electrons and not light, so has a lower wavelength and higher resolution

Question 21

What is a TEM

Answer 21

Stands for a transmission electron microscope

Question 22

What happens in a TEM

Answer 22

An electromagnetic coil focuses electrons onto a specimen and onto a screen or photographic plate for viewing.

Question 23

What is the resolution and magnification of a light microscope

Answer 23

200nm (resolution), x1500-2000

Question 24

What is the resolution and magnification of a TEM

Answer 24

0.2-0.5nm, x500,000 - 2,000,000

Question 25

What is a SEM

Answer 25

A scanning electron microscope

Question 26

What happens in a scanning electron microscope

Answer 26

Electromagnetic coils are used to scan the surface of a specimen with electrons, specimens are coated with gold and silver. Reflected electrons are collected and focused onto a viewing screen or camera.

Question 27

Why must both electron microscopes be done in a vacuum

Answer 27

Air particles SCATTER electrons so it must be done in a vacuum. More dense objects scatter more electrons than less dense objects.

Question 28

What is a graticle

Answer 28

Is a fixed scale inside an eyepiece. The divisions can be used to measure a magnified image, but you need to calibrate it.

Question 29

What is a stage micrometer

Answer 29

It’s a 10mm scale etched into a slide with subdivisions of 0.1mm.

Question 30

How do u use a stage micrometer and graticle

Answer 30

We place the stage onto the stage under low power so you can see the graticle and stage micrometer. You then find the number of eyepiece graticle units to stage micrometer units.

Question 31

How do you measure specimens

Answer 31

You find the number of units in 1 eyepiece graticle unit and then multiply by the number of eyepiece graticle units in the specimens length or width.

Question 32

What are the advantages of using a light microscope

Answer 32

inexpensive to buy and operate Small and portable simple sample preparation Sample preparation doesn’t usually lead to distortion Vacuum is not required Natural colour of sample is seen Specimens can be living or dead

Question 33

What are the benefits of electron microscopes

Answer 33

Magnification and resolution

Question 34

What is the resolution and magnification of a SEM

Answer 34

3-10nm and x100,000 - 500,000