Practical 1

Question 1

Why are light microscopes commonly called (compound) light?

Answer 1

Because there are 2 lenses magnifying the specimen; The ocular & objective.

Question 2

How do you calculate the total mag of a light microscope?

Answer 2

The ocular X objective

Question 3

Label number 1 and state it’s function

Answer 3

Base- supports the Microscope

Question 4

Label number 2 and state it’s function

Answer 4

Light source- provides light

Question 5

Label number 3 and state it’s function

Answer 5

Diaphragm- controls how much light the specimen receives.

Question 6

Label number 4 and state it’s function

Answer 6

Stage- the place where the slide is placed

Question 7

Label number 5 and state it’s function

Answer 7

Stage clip- holds the slide in place

Question 8

Label number 6 &7 and state it’s function

Answer 8

High power objective lens (or low)- further magnify the specimen (requires oil immersion for high power)

Question 9

Label number 8 and state it’s function

Answer 9

Nose piece- holds the objective lenses

Question 10

Label number 9 and state it’s function

Answer 10

Arm- supports the upper part of the microscope and is used to carry the microscope.

Question 11

Label number 10 and state it’s function

Answer 11

Fine focus knob- focuses high power objective lens

Question 12

Label number 11 and state it’s function

Answer 12

Tube- light travels through

Question 13

Label number 12 and state it’s function

Answer 13

Coarse focus knob- focuses low objective lens

Question 14

Label number 13 and state it’s function

Answer 14

Eyepiece lens- magnifies the specimen

Question 15

At a high power field, the magnification is 100x and diameter is 4mm

whar would the diameter be under a low power field, where magnification is 50x?

Answer 15

8mm

Question 16

Describe flourescence microscopy

Answer 16

it is a method of microscopy that is based on the fact that some materials are able to give out energy, in the form ofvisible lightwhenirradiated. Sometimes natural substances such as chlorophyll react appropriately, other times adye is needed to give out visible light.

Question 17

Why do fluorescent materials give out energy in the form of light?

Answer 17

• the photons excite the electrons of the material
• the electron jumps to excited state
• unstable electron moved back and gives out energy in form of light of higher wavelength

Question 18

What is fluorescent microscopy used for?

Answer 18

detecting structures, molecules, or proteins in a cell.

Question 19

Give 2 dyes that are used in fluorescence dyes, what color light are needed to activate them, and what color they emit.

Answer 19

• Fluorescein- emits green light when it is excited by blue light
• rhodamine- emits deeps red light when it is excited by green-yellow light

Question 20

How many fluorescent filter cubes do fluorescence microscopes have and what do they each contain?

Answer 20

There are 3 filter cubes, each containing specific barrier filters and a beam splitting mirror

The filter cubes provide blue, green-yellow, and UV light