7999729
Description
Mind Map by Aleena Sheraz, updated more than 1 year ago
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Created by Aleena Sheraz
almost 8 years ago
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2.1.3 Measuring objects seen with a light microscope
- Using graticules
- Microscope eyepiece= fitted with graticule
- Graticule= transparent with a
small ruler etched on
- The scale is arbitrary -
represents diff. lengths at diff.
magnifications
- The scale is arbitrary -
represents diff. lengths at diff.
magnifications
- As a specimen is viewed the eyepiece
graticule scale is superimposed and the
dimensions of specimen can be measured in epu
- Eyepiece scale has to be
calibrated for each different
objective lens by using a stage graticule
- Stage graticule= precise measuring divide
with a small scale to calibrate value of
eyepiece divisions at different
magnifications
- Stage graticule= precise measuring divide
with a small scale to calibrate value of
eyepiece divisions at different
magnifications
- Graticule= transparent with a
small ruler etched on
- Microscope eyepiece= fitted with graticule
- Using a stage graticule to calibrate
the eyepiece graticule
- A stage graticule, microscopic ruler, is
placed on the microscope stage
- Ruler is 1mm long with 100 divisions=
each division is 0.01mm or 10um
- Ruler is 1mm long with 100 divisions=
each division is 0.01mm or 10um
- 1) Insert eyepiece graticule in X10
eyepiece of microscope
- 2) Place a stage graticule on microscope
stage, bring to focus, use low power X4
objective. T. magnification= X40
- 3) Align eyepiece and stage graticule. Check
value of 1 eyepiece division
- 4) In the example, stage graticule
(1000um) corresponds to 40 eyepiece
divisions
- 5) Each eyepiece division=
1000/40 = 25um
- 6) Now use X10 objective lens (T.
magnification is X100) and focus
on stage graticule
- 7) Align both
graticules
- 8) From the example, 100 eyepiece divisions correspond with
1000um
- 9) So one eyepiece division= 1000/100=
10um
- A stage graticule, microscopic ruler, is
placed on the microscope stage
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