Answer to Question #219252 in Organic Chemistry for miss Claire Yeboah

Question

is asked to calibrate a microscope and provided with both a stage micrometer and
an eyepiece (ocular) graticule.

The stage micrometer is marked off in a scale for 1mm and shows 10ths and 100ths.

a) How many micrometres are represented between a 10th division and the next? Show how you have arrived at your answer. (2 marks)









The student estimates that there are 47 ocular units to the full mm scale of the stage micrometer using the X4 objective lens for the particular microscope they are using.

Show how the student would calculate the value of 1 ocular division in micrometres to two decimal places.

Answer 1

Now it is just a simple math ratio. 30 divisions of the reticle (eyepiece micrometer) equal 200 micrometers. So what does one division on the reticle equal. Let's see, 30 is to 200 as one is to X. Two fractions, 30 over 200 equals 1 over X. Cross multiply, you get 30X=200um, solve for X by dividing both sides by 30 and X4 equals 6.7 um. Notice that they line up again at 60 but alignment is off by one at 90. If we use 90 and 61 (610um) we get 6.8um. The wider the interval, the more accurate your results should be.