Microscope Measurements and Calculations - 3.3 Flashcards
What is the piece of equipment that can be used to measure the size of objects when using a light microscope?
The eyepiece graticule.
How does the eyepiece graticule work?
The graticule is a glass disc that is placed in the eyepiece of a microscope. A scale is etched on the glass disc. This scale is typically 10mm long and is divided into 100 sub-divisions. The scale is visible when looking down the eyepiece of the microscope.
Why can the eyepiece graticule not be used directly to measure the size of objects under a microscope’s objective lens and how is this overcome?
Each objective lens will magnify to a different degree. The graticule must first be calibrated for a particular objective lens. Once calibrated in this way, the graticule can remain in position for future use, provided the same objective lens.
Why is it sensible to record the results of the calibration of the graticule of a particular objective lens and to leave this attached to the microscope?
This will save you having to recalibrate each time you want to measure the size of the object being viewed under the microscope.
What piece of equipment do you need to calibrate the eyepiece graticule?
A special slide called a stage micrometer.
What is a stage micrometer?
A slide that has a scale etched into it. Usually the scale is 2mm long and its smallest sub-divisions are 0.01mm (10nm).
What can you calculate when the eyepiece graticule scale and the stage micrometer scale are lined up?
The length of the divisions on the eyepiece graticule.
