Microscopes

Question 1

Used

Answer 1

to magnify objects and make them appear bigger

Question 2

Total Magnification =

Answer 2

eyepiece magnification X objective magnification

Question 3

Low Resolution

Answer 3

wavelength of light is too long to resolve between close objects
light diffracts when it passes through a gap similar length to its wavelength

Question 4

more magnification help? (light)

Answer 4

magnifying more won’t add any more detail

you can not see objects that are closer together than the wavelength of light as separate objects

Question 5

Electron Microscope

Answer 5

have a shorter wavelength

resulting in high-resolution images

Question 6

more magnification help? (electron)

Answer 6

you can magnify to reveal more detail

2 objects closer than the wavelength of visible light can be distinguished

Question 7

magnification

Answer 7

how many times larger an image appears

Question 8

resolution

Answer 8

the minimum distance between 2 objects before they appear as one

Question 9

advantages of light microscopes

Answer 9

live specimens

internal structures

Question 10

disadvantages of light microscopes

Answer 10

poor resolution

need thin specimens

Question 11

advantages of electron microscopes

Answer 11

highest resolution

internal structures

Question 12

disadvantages of transmission electron microscopes

Answer 12

dead specimens
need thin specimens
artefacts

Question 13

advantages of scanning electron microscopes

Answer 13

high ressolution
3D image
specimen can be thick

Question 14

disadvantages of scanning electron microscope

Answer 14

dead specimen only
artefacts
can not view internal structures

Question 15

Image =

Answer 15

Actual X Magnification

Question 16

1m — 100um

Answer 16

unaided eye

Question 17

5cm —- 50nm

Answer 17

light microscope

Question 18

100um —

Answer 18

electron microscope

Question 19

Graticule

Answer 19

used to measure images seen through a light microscope

Question 20

Eye Piece Graticule

Answer 20

glass disc placed in the eyes piece
usually 10mm in size with a scale of 0-100
1 unit = 0.1 mm = 100um

Question 21

Calibration Using a Stage Micrometer

Answer 21

place a graticule in the eyepiece of the microscope,
place a stage micrometre slide onto the stage,
line up the eye piece graticule and the stage micrometre,
look along the scales until you see 2 points that match up,
divide the value on the graticule scale by the value on the stage micrometre to give a value for 1 unit of the stage micrometre,
each unit equals 10um so to calculate the actual length of one unit on the graticule scale you divide 10 by your previous number,
now as you measure images through this objective lens you can multiply this number by the units it measures.