Exercise 1: The Microscope

Question 1

Objects that are smaller than ____________ of a millimeter cannot be seen by the naked eye.

Answer 1

one-tenths

Question 2

Which type of microscopy uses light to illuminate specimens and creates images where the specimen is dark and set against a bright background?

Answer 2

Light microscopy

Question 3

Which types of microscopes use a two-lens system to obtain images of thin, minute specimens such as tissue sections and blood smears?

Answer 3

Compound light microscopes

Question 4

Explain how to properly carry a microscope.

Answer 4

When carrying a microscope, hold it with one hand by the arm and support the base with the other.

Question 5

How far from the table should a microscope be placed?

Answer 5

A microscope should be placed at least three centimeters from the edge of the table.

Question 6

Which part of the microscope is the vertical extension of the base?

Answer 6

pillar

Question 7

Which part of the microscope connects the arm and pillar?

Answer 7

inclination joint

Question 8

Which part of the microscope controls the movement of the stage clips?

Answer 8

stage control knob

Question 9

Which parts of the microscope are connected to the eyepiece?

Answer 9

draw tube and body tube

Question 10

Enumerate the four types of objective lens and their respective magnification.

Answer 10

• low power object (10x)
• high power objective (40x)
• scanning objective (4x)
• oil immersion objective (100x)

Question 11

Which two knobs control the movement of the stage at smaller and greater intervals?

Answer 11

fine adjustment knob and coarse adjustment knob

Question 12

Give the two reflecting surfaces of a mirror attached to the pillar of a microscope.

Answer 12

plane and concave

Question 13

Which part of the microscope focuses light onto the specimen?

Answer 13

condenser

Question 14

Which part of the microscope regulates the amount of light passing through the aperture?

Answer 14

Iris diaphragm

Question 15

Which term refers to the condenser and iris diaphragm?

Answer 15

substage

Question 16

Which solvents can be used to wipe off persistent residue in microscopes?

Answer 16

distilled water, 90-100% ethanol, acetone

Question 17

Which solvent is recommended when removing thick substances such as immersion oil and hydrophobic stains in microscopes?

Answer 17

Xylene

Question 18

TRUE or FALSE:
For microscopes with mirrors, set it in a vertical position, facing sideways, before storage.

Answer 18

TRUE

Question 19

TRUE or FALSE:
For electrical microscopes, set the control for brightness to the lowest level and set the power switch to the off button.

Answer 19

TRUE

Question 20

TRUE or FALSE:
Set the revolving nosepiece to the lowest possible objective.

Answer 20

TRUE

Question 21

TRUE or FALSE:
For microscopes with an adjustable body tube, the lowest objective should be at least one centimeter above the stage.

Answer 21

TRUE

Question 22

TRUE or FALSE:
For microscopes with an adjustable stage, the stage should be set at the lowest level.

Answer 22

TRUE

Question 23

TRUE or FALSE:
When turning the revolving nosepiece, do not apply pressure on the objective. Place your fingers directly on the nosepiece.

Answer 23

TRUE

Question 24

TRUE or FALSE:
Use the concave surface of the mirror if the external light source is dim.

Answer 24

TRUE

Question 25

TRUE or FALSE:
Keep both eyes open when looking through the eyepiece.

Answer 25

TRUE

Question 26

TRUE or FALSE:
Tilt the microscope only when the specimen is held in place by the stage clips.

Answer 26

TRUE

Question 27

TRUE or FALSE:
When using LPO, turn the coarse adjustment knob until the objective is about 16 mm above the specimen while looking on one side of the microscope.

Answer 27

TRUE

Question 28

TRUE or FALSE:
If the adjustment knobs are located on both sides, always turn them simultaneously using both of your hands.

Answer 28

TRUE

Question 29

TRUE or FALSE:
The object is more or less focused when the HPO is 4 mm above the stage.

Answer 29

TRUE

Question 30

Which property refers to the ability of the microscope to distinguish two points of an image?

Answer 30

resolution

Question 31

What refers to the relative size of the final image seen by the eye to the object after light passes through the objective and eyepiece.

Answer 31

linear or total magnification

Question 32

Which property refers to a number between 0 and 1 that denotes the resolving power of an objective?

Answer 32

numerical aperture

Question 33

Which property refers to the ratio of the size of a drawing to that of the object drawn?

Answer 33

magnification

Question 34

Give the formula for magnification

Answer 34

magnification = size of drawing/size of specimen

Question 35

Which instrument used for measuring microscopic structures possesses a graduated scale with no inherent value?

Answer 35

eyepiece micrometer

Question 36

Which instrument refers to a slide provided with a scale with known values, usually in tenths and hundredths of a millimeter?

Answer 36

stage micrometer

Question 37

Give the formula for the calibration constant.

Answer 37

c = [(# of SMD x 0.01 mm/SMD) / (# of EMD)] (1000 μm/mm)

Question 38

Give the formula for calculating the size of a microscopic object given the number of EMDs spanned by the it’s length.

Answer 38

I = (# of EMD) (c)