microscopes

Question 1

what is resolution

Answer 1

the ability to distinguish two points on an image

Question 2

what is resolution limited by

Answer 2

resolution is limited by the wavelength of the illuminating source

Question 3

what is the wavelength of visible light

Answer 3

400-700nm

Question 4

what is the wavelength of an electron beam

Answer 4

2nm

Question 5

what is the ‘rule of thumb’ when calculating microscope resolution

Answer 5

the resolution is usually half of the wavelength

Question 6

what is the resolution of visible light

Answer 6

200nm

Question 7

what is the resolution of an electron beam

Answer 7

1nm

Question 8

how would you calculate the magnification power on a microscope

Answer 8

eyepiece * objective lens

Question 9

what is the magnification of the eyepiece lens

Answer 9

10x

Question 10

what are the two types of electron microscopes

Answer 10

TEM, SEM

Question 11

principles of TEM

Answer 11

Electrons pass through thin specimen. Denser parts absorb more electrons, so denser parts look darker. Electrons have short wavelengths so they have a higher resolution.

Question 12

what happens in SEM

Answer 12

beam of electrons is bounced off the surface. creates a 3d image

Question 13

what type of electron microscope is 3d

Answer 13

SEM

Question 14

is TEM 2d or 3d

Answer 14

2d

Question 15

do electron microscopes show images with light

Answer 15

no, they are black and white.

Question 16

what must be a requirements for a specimens under a electron microscope

Answer 16

they must be dead. Must be in a vacuum.

Question 17

a specimen is living, which microscope should you use ?

Answer 17

light microscope

Question 18

what is an artefact

Answer 18

damage is caused by preparation technique. eg air bubbles

Question 19

limits of TEM

Answer 19

cannot be living. Must be in a vacuum. artefacts present. Complex staining method. Image not in 3d