Thank you so much first day of sixthform had biology and couldn’t get around the stage micrometer and eye piece graticule but your video has explained clearly and I can now get on with my homework
Thank you very much. I am a student at the university of Manchester and we need to learn how to do this as first year students. They failed to explain it but you have explained it perfectly here. Your teaching style is perfect!
Usually only look at the big subscriber RU-vid channels for this like free science lessons etc but this is the only video that’s helped and I fully understand thank you!
Hi! Great video! I have a question, I see that all this calibration is made every time I need to use a different objective, 4X, 10X, etc But my question is if I need to calibrate again if I change the sample thickness, since I move the coarse and fine focus to focus the right layer. This question does not let me sleep. thanks!
Hi Jo, I believe you added an extra '9' in your conversion to µm with the 4x objective, as you had the 10 e.g.u. equal to 0.99 mm, not 0.999 mm. So the result should be 99.0 µm per epg unit not 99.9.
Great video and it's very clear! But I have one question from the past paper that I still don't understand. If it's possible, where can I contact you? Thank you very much
Sorry for not replying sooner. Do you mean the higher the magnification, the more precisely we can measure? Yes, you will be increasing the precision, but only because the eyepiece graticule scale becomes finer. Precision is to do with the measuring instrument you use (how small are the divisions).
Thanks for sharing! Very clear. Just wanna know why don't we have an objective graticule which comes with a given objective? In this way, wouldn't it be easier to calculate the item's size without calibration?
Hi. That’s a good idea and to be honest, I don’t know. I assume it’s something to do with the way microscopes are made which prevents a graticule from being placed in the objective lens. Could also just be because lenses can be swapped in and out of a microscope, so it might just be too expensive to put graticules in all objective lenses.
Hello, thank you for the video. It was very helpful. At 11:23, I chose to do 6egu = 2.3mm and the answer I got was 1egu = 0.383 mm, but you got 0.038mm. Can you tell me why my answer is wrong? Thank you:)!
Hi. I'm not quite sure what you mean. When you say mm, do you mean micrometers? And when you say you chose to do 6egu = 2.3 mm, where did you get this from?
Hi there, I have just found your channel, could you please tell me if your content follows Cambridge international Examinations or another exam board? Thanks
Hi Alex, I'm so sorry for not replying, I must have missed it. Yes, everything is CIE. The biology itself will obviously be the same as for other exam boards, but the level of detail and emphasis may be different.
I'm not sure what you mean? The eyepiece graticule scale is different, depending on the objective lens you are using. That's why you need to calibrate it using the stage micrometer.
Hi. Sorry for the late reply. I think I must have been working without rounding? Tbh I’m not sure but I’ll go back and have a look. It shouldn’t make any difference to the understanding of the concept and calculations though.
If you do this in real life, you would look at the stage micrometer and it will tell you. This is because you can get stage micrometers with different scales. In my video, I used those divisions as they tend to be more common. In an exam question, they would also tell you the size of the divisions (so don't assume it's always 0.1 mm!)
Hi. You work out the length of the eyepiece units by using the stage micrometer. When we lined them up, 10 eyepiece graticule units matched up with 9.9 stage micrometer divisions. We know each stage micrometer division is 0.01 mm. 9.9 x 0.01 = 0.099 mm. So that’ the length of 1 eyepiece graticule unit (1 egu). There is no 99.9 mm, you have the wrong units. I converted 0.099 mm into micrometers (1 mm = 1000 micrometers). Watch the video again and try to follow through the explanation again.
