Microscopic Measurements And Calculations

Question 1

how do you measure cells?

Answer 1

-using an eyepiece grativule

Question 2

what is the eyepiece graticule?

Answer 2

• a glass disc that is placed in the eyepiece of a microscope
• there is a scale etched in the glass disc typically 10mm long and divided into 100 sub divisions
• the scale is visible when looking down the eyepiece of ten microscope

Question 3

how do you use an eyepiece graticule?

Answer 3

• it cannot be used to directly measure the size of objects under the microscopes objective lens as each lens magnifies to a different degree
• the graticule must be calibrated for a particular lens
• it’s sensible to record the results of the calibration for a particular objective lens and leave it with the microscope so you don’t have to recalibrate each time

Question 4

how do you calibrate the eyepiece graticule?

Answer 4

• you need to use a stage micrometer
• line up the eye piece graticule scale and the stage micrometer stage
• this allows you to see how many 10 units on the micrometer scale are equivalent to on the graticule scale
• you then find how much one unit of the micrometer scale is worth and divide it by 10 to work out the um

Question 5

what is the stage micrometer?

Answer 5

• it’s a skied that has a scale etched into it

- the scale is 2mm long and it’s smaller sub divisions are 0.01 mm

Question 6

how do you calculate linear magnifications of drawings and photographs?

Answer 6

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Question 7

how do you calculate the actual size of specimens from drawings and photographs?

Answer 7

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Question 8

How do you work out the scale for the different objective lenses?

Answer 8

-divide the differences in magnification by of the new lens by the magnification of the original lens then divide that calibration for the original microscope by the difference in magnification do the two lenses