Experimet A : The microscopic measurement of microorganisms

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     Assalamualaikum and a very good morning everyone.... The experiment I did in this week (fifth week) is about the how we measure the microorganisms. Because microorganisms are too tiny and we cant see in our naked eyes. As usual Dr. Adelene taught us how to measure. But majority in my class were not understand what Dr. Adelene said including myself 😂😂😂 . Later on, our demostrated also taught again what Dr.Adelene said. The demostrated came to every group and taught and shown us how to measure it. Encik. Zainudddin also gave some demo. Firstly, I opened the ocular (eyepiece lens) and put the ocular micrometer inside the ocular lens. Then, I was placed the stage micrometer on the stage and adjusted the coarse-adjustment knob until I got found the two scales. Next, I superimposed on the each other of the scales and calibrated it. This week experiment was simple and will be more focused. I got learned something new in this week how to measure the microorganisms. Because when I'm in secondary school or in matriculation, I never learnt about it. I just got learned how to saw the microorganisms under microscopes only. Now I'm as a microbiology student , I have study more even more about microorganisms. So, I'm going to share the informations about this experiment which is the microscopic measurement of microorganisms.

   Measurement of the dimensions of microorganisms is done under microscope with the two micro-scale called "micrometers". Both the micrometers have microscopic graduations etched on their surfaces. The ocular micrometer which is placed inside the eyepiece, is a glass dics graduation etched on its surfaces. The distance between this graduations will vary depending on the objective being used, which determines the size of the field. This distance is determined by using a stage micrometer is a glass slide with etched graduation that are 0.01mm or 10 micrometers apart. The calibration procedure for the ocular micrometer reqiures that the graduations on both micrometers be superimposed on each other by rotating the eyepiece. The number of ocular divisions coinciding with the number of stage divisions is found out. After the calibration, the stage micrometer is removed and the microbe, whose dimensions are to be measured, is placed on the stage on a slide and focused. Then, the number of ocular divisions occupied by the microorganism is counted. By multiplying, this number of divisions with the calibration factor, the size of the microbe is determined.


    It is possible to measure the size of microbes by directly observing them on a stage micrometer. This would avoid calibration and calculations. But the stage micrometer is a standard scale, which is costly because of the micro etchings on it. If used frequently for direct observations, its etchings get worm away. Moreover, the etchings on the stage micrometer are more widely spaced than those on the ocular micrometer. Thus, the dimensions cannot be precisely determined with a stage micrometer. That is why it is never used for direct measurement.

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