Microscope and Drawings

Question 1

what is the basic function of a microscope?

Answer 1

to magnify the apparent size of objects –> allowing for the user to see details that are invisible to the unaided eye such as allowing cells to become visible

Question 2

what is the maximum resolution of the unaided human eye? what about with a compound light microscope?

Answer 2

• approx 0.1 mm

- approx 0.0002 mm

Question 3

how does a compound microscope illuminate specimens? how does a transmission electron microscope illuminate specimens? which has a stringer resolving power?

Answer 3

compound –> with light
transmission –> with electrons
-TEM has a resolving power about 400X greater

Question 4

what is a stereoscope used for? what magnification is it good up to?

Answer 4

designed mainly for looking at the surface detail of objects –> allows for examination of larger intact specimens
-only useful up to 40X magnification

Question 5

what happens when you switch from a lower power objective to a higher power objective?

Answer 5

the image gets larger

Question 6

how is the overall magnification of an image calculated? what is the magnifying power of the eyepiece (ocular lens)? what is the magnification of the objective lens? what are the overall magnifications for the three powers?

Answer 6

calculated as the product of the magnifying powers of the objective lens and the eyepieces

• ocular lens –> 10X
• objective lens –> low = 4X; medium = 10X; high = 40X

overall magnification:
40X, 100X, 400X

Question 7

what is the field of view? field of view gets … as you switch from a low power to a higher power

Answer 7

the circular area of the slide that is visible through the eyepiece
-gets smaller

Question 8

how do you determine actual size of an object?

Answer 8

1. set microscope at highest power for which the object is visible completely in field of view
2. select convenient dimension of specimen and estimate how many times the length would fit across the field of diameter
3. divide the field diameter (4.3mm; 1.85mm; 0.4mm) by the number of cells that would fit across it

Question 9

what is depth of focus?

Answer 9

amount of thickness that is in focus

Question 10

what must the material being studied under a compound microscope be?

Answer 10

-thin enough to transmit light

Question 11

what are the rules for biological drawings?

Answer 11

1. use pencil
2. should occupy 1/4 - 1/3 of a page
3. simple line drawings, no sketching, only stippling, no shading
4. must include:
   - descriptive figure caption (including common and Latin name)
   - appropriate labels –> on outside of drawing, connected with line from ruler
   - microscope total magnification
   - actual size calculation of specimen
   - scale bar outside of drawing