Microscopes

Parts of a microscope

Resolution- The ability to show detail

Body tube- Keep the proper distance between lens

Ocular lens (eye piece)- look through it

Revolving nosepiece- Allows you to choose which lens

Objectives- lenses that provide three levels of magnification

Stage clips- holds the slide in place 

Diaphragm- regulates the amount of light

Light source- Illuminator produces light 

Arm- Supports the body tube

Stage- supports the slide

Coarse adjustment knob- moves the stage a lot for focusing

 Fine adjustment knob- moves the stage a little for focusing

 Base- supports the microscope 

Light microscope 

 How it works:  glass lenses blend light and magnify the object.

•  Advantage:  relatively cheap and easy to use, you can see living things and life processes at work like fluid uptake and movement.

•  Disadvantage:  They only magnify so much-  at most 1000x 

Scanning Electron microscope

How it works: A beam of electrons is used instead of light. the cell surface is examined after it has been coated with a thin layer of metal.

• Advantage: You can see great detail of the outside of an object. It can magnify a lot up to 500,000x or more.

•  Disadvantage:  They are very expensive, you need special training, and the organism is killed

Transmission electron microscope 

 How it works: specimens are cut into extremely thin sections and stained with atoms of heavy metals. A beam of electrons is aimed through the slice. You get a 2D image

• Advantage: you can see great detail of the inside of an object. it can magnify a lot up to 500,000x or more

•  Disadvantage: They are very expensive, you need special training, and the organism is killed

Calibrating the microscope

Total magnification = Ocular Lens X Objective Lens

Low Power    10 x 4 = 40x

Medium Power    10 x 10 = 100x

High Power    10 x 40 = 400x

Diameter of the field of view

Low Power- 4.5 mm

Medium Power- 1.8 mm

High Power- 0.45 mm