Microscopes

Question 1

Measuring samples under the microscope

Answer 1

Line up 2 scales and find a place where EG and SM line up
Find how many divs equals 1 EG
Multiply SM by 100 to find um

Question 2

Magnification equation

Answer 2

Magnification=size of image/size of real

Question 3

Resolution

Answer 3

Minimum distance apart 2 objects need to be in order for them to appear as separate items
Depends on wavelength of light/radiation
Increasing magnification does not always increase resolution
Smaller wavelength for smaller objects

Question 4

Light microscope magnification

Answer 4

1500x

Question 5

Electron microscopes magnification and resolution

Answer 5

Best mag 500000x
Best res 0.1nm
Needs a vacuum, electrons will be deflected by air 
Beam focused with electromagnets
Images=photomicrographs

Question 6

Scanning electron microscope resolution

Answer 6

Res 20nm
Shows surface view, electrons do not penetrate specimen
Does not need to be thin

Question 7

Transmission electron microscope

Answer 7

V thin section
Dark areas absorbed electrons, light areas let electrons pass through
Cannot see surface structures

Question 8

Limitations of electron microscopes

Answer 8

Resolution not always achieved
Difficult to prepare specimen, high energy beam of electrons can destroy samples
Cannot observe living specimens due to vacuum
Complex staining process, not a colour image
Specimens must be v thin for TEM
Artefacts