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Metric measurement and microscopy
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The metric system Standard system of measurement in sciences
Length, weight, volume, tempreture
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Metric units of length Length: meter (m), centimeter (cm), millimeter (mm), micrometer (µm), nanometer (nm) 1m=100cm 1cm=10mm 1mm=1,000 µm 1µm=1,000nm 1m= 1×102cm= 1×103mm= 1×106 µm= 1×109nm 1nm= 1×10-3µm= 1×10-6mm= 1×10-7cm= 1×10-9m
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Metric units of length
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Metric units of length What is your height?
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Metric units of weight Weight: gram (g), milligram (mg)
1g=1,000mg= 1×103mg 1mg=0.001g= 1×10-3g
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Metric units of weight Using scale to measure the weights of small objectives
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Metric units of volume Volume: liter (l), milliliter (ml)
1l=1,000ml= 1×103ml 1ml=0.001l=1×10-3l
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Meniscus Reading
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Temperature scales Fahrenheit (F) & Celsius (C) C= (F-32°)/ 1.8
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Microscopy Microscopes Illumination source Magnification
Sliced section image Three dimension image Light microscope light rays lower (2000 times) regular light microscope stereo-microscope Electron electron beams higher (over 500,000 times) transmission (TEM) scanning electron microscope (SEM)
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Use of the compound light microscope
Pick up the microscope carefully Never touch the lens with fingers. Use ONLY lens paper to clean the glass Don’t loss the key
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The compound light microscope
Two sets of lenses —the ocular lenses —the objective lenses The light only passes through clear portions, not opaque portions The objects must be small or thinly sliced sections
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Total magnification = magnification of the ocular lens × magnification of the objective lens
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Identifying parts of microscope
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Focusing the compound light microscope
Always begin focusing with the lowest power objective Use coarse-adjustment knob ONLY with low-power objective Make sure the nosepiece is on the lowest power objective when done with the scope assignment Clean all slides, materials and work area
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Field of view* Low-power objective has larger field of view
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Depth of field* High-power objective has narrower depth of view
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Microscopic Observations
Prepared slides Onion Euglena
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Plant cell (root tip cell)
Gills of a fish
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