Microscopy

Question 1

List the 3 main types of microscopes.

Answer 1

Dissecting microscope
Compound light microscope
Electron microscope

Question 2

Properties of the compound light microscope?

Answer 2

Two lens systems
Specimen illuminated from below below
Image formed by the objective lens and re-magnified by tge eyepiece lens

Question 3

List the parts of the compound microscope. (9/12)

Answer 3

Base
Light source
Diaphragm
Objective lens
Revolving nosepiece
Tube / turret
Coarse adjustment knob
Fine adjustment knob
Eyepiece lens / ocular lens
Stage
Arm
Stage clips

Question 4

What does the base do?

Answer 4

Provides support

Question 5

What does tge light source do?

Answer 5

Light bulb provides light to make the object on the slide visible
In some microscopes the light bulb is repaced by a mirror which reflects light

Question 6

What does the diaphragm do?

Answer 6

Operated by a small lever, used to control the amount of light shining through the object

Question 7

What do stage clips do?

Answer 7

Attached to the stage anchor the slide which contains the object to bw viewed

Question 8

What do the objective lenses do?

Answer 8

Magnifies the object.
Three lenses: 4x (short lens), 10x and 40x (longest lens)

Question 9

What does the nosepiece do?

Answer 9

Rotated to move different objective lenses into position

Question 10

What does the tube/turret do?

Answer 10

Separates the objective lens and eyepiece

Question 11

What does the coarse adjustment knob do?

Answer 11

Used to bring the stage closer to tge objective lens to focus in on the object on the slide

Question 12

What does the fine adjustment knob do?

Answer 12

Used when using higher magnification lenses to make fine adjustments that will bring the object into focus

Question 13

What does the eyepiece/ocular lens do?

Answer 13

Magnifies the object formed by the objective lens. Always provides 10x magnification

Question 14

How do you calculate the total magnification? (Compound microscope)

Answer 14

Multiply the magnifications of the eyepiece (10x) and the objective lens
e.g. total magnification for 4x objective lense
4×10=40x

Question 15

List some differences between the compound and dissecting microscopes.

Answer 15

.Dissecting is used to examine small but NOT MICROSCOPIC objects.
Compound is used to examine MICROSCOPIC objects.
.Compound is illuminated from below
Dissecting is illuminated from above
.Compound has 1 eyepiece lens and 3 objective lenses
Dissecting has 2 eyepiece lenses and 1 objective lens
. Compound has 1 tube/turret
Dissecting has 2 tubes/turrets
. Compound adjustment knob adjusts the stage
Dissecting adjustment knob adjusts the height of the lenses

Question 16

How do you calculate the actual size of an object using a scale bar?

Answer 16

. Measure length of specimen in mm
. Measure length of scale bar in mm
. Divide length of specimen by length of scale bar (answer has no units)
. Multiple the last answer by the scale bar label (answer in same unit as scale bar label)

Question 17

How do you calculate the actual size of an object using the magnification factor?

Answer 17

. Measure the length of the specimen in mm
. Convert the length of the specimen image to micrometers (*funky u + m)
(Times by 1000)
. Divide the length of the specimen by the magnification (answer in micrometers)
e.g. length of specimen = 83mm
Convert to micrometers = 83000 funky u + m
83000 um / 320 = 260um

Question 18

When would an electron microscope be used?

Answer 18

To get clear images of objects at very high magnifications

Question 19

What is the difference between TEM and SEM?

Answer 19

TEM (Transmission Electron Microscope)
SEM (Scanning Electron Microscope)
TEM can see inside the specimen
SEM can see outside of the specimen
TEM visible because electrons cast shadows whike passing through the specimen
SEM visible because electrons bounce off the specimen