Transcript Microscope - USD305.com

Sec. 4- Tools and
Procedures
• Metric system-decimal system of
measurement whose units are based
on certain physical standards
– Scaled on multiples of ten
Length
1 m= 100 cm
Mass
Volume
Temperature
1 kg= 1000 g
1 L= 1000 mL
0 deg Cel=
freezing pt of
water
1 m= 1000 mm
1 g= 1000 mg
1 L= 1000 cm3
100 deg C=
boiling pt of
water
100 m= 1 km
1000 kg= 1
metric ton
Microscope
• What is the most widely used tool in
biology?
– Microscope
• What is a microscope used for?
– View object too small to be seen with the
naked eye.
• How does a microscope enlarge an object?
– By magnification with lenses
• What is magnification?
– It is a microscope’s power to increase an
object’s apparent size.
Light Microscope
• This microscope uses a beam of light (sun or light
bulb) to pass through a series of lenses to
produce an enlarged image.
– Can use it on dead or alive organisms
– Can magnify the object a 1000 times
• 2 lenses used in the light microscope
– 1. Objective lens – closest to the specimen
being viewed. Usually 3 objectives.
– 2. Eyepiece (ocular lens) – closest to the eye
• How is magnification figured in a microscope?
– Eyepiece magnification X Objective
magnification
Electron Microscope
• An electron microscope works by beam of
electrons being shot onto the specimen,
which enlarges the object as an image.
• You cannot observe living organisms with
this microscope.
• 2 main types of electron microscopes
– 1. Transmission electron microscope
(TEM) – uses an extremely thin sliced
specimen.
• It magnifies all the way up to 2 million
times.
2. Scanning electron microscope (SEM) –
scans the surface of an object through the
use of an electron beam. The object is
prepared by covering the object with a
thin layer of gold and platinum spray. The
image produce is a 3-D image.
• It magnifies the image 50,000 to 100,000
times.
• Copies can be printed off from the
image.
• It costs between $30,000 – $80,000
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Microscope Parts
1. Field- area seen through the
eyepiece.
2. Eyepiece or Ocular lens
3. Course focus- used first when
focusing
4. Fine focus- to fine focus the object.
5. Low power- field is larges and
least magnified.
6. High power- field is smallest and
most magnified.
• 7. Diaphragm- regulates amount of
light allowed in.
• 8. Objective- adjustable lenses.
• 9. Resolution- the clarity of the
field.
• 10. Micron- microscope’s unit of
measurement.
• Light Microscope is limited to
about 1,000 X.