MICROSCOPE CALIBRATION USING STAGE MICROMETER (All exams)

[@jasminpanesar3036]

This is so helpful. Throughout AS and most of A2 I've been lost when it comes to calibrating microscopes and now I finally understand. Thank you!

[@jessicadausas6093]

This is so much better than all the other videos on calibration cause they blab on about unnecessary stuff

[@neeshizzlesizzle3244]

I finally get it, gonna cry

[@agrirevolutionagricoaching2957]

Very good explanation..thank u sir

[@alittleramble]

You safe my life. Thank you so much !

[@soyadrink9831]

11:59 don't we start counting from the very first line (for stage micrometer scale)? Because I can see six lines, but it says 5 s.m.u

[@alevelbiologymrashcroft8177]

It’s the “overlap” between the stage micrometer and the eye piece graticule.

[@urjamhatre9916]

Thank you so much! This video was extremely helpful to me

[@emlynn4070]

Beautifully executed.

[@meewmei]

Great explanation ❤️

[@meliasummers6730]

14:31 Amazing video , I have a question about the wording of the actual size , wouldn't you then divided it by 10 since it's magnified by x10 ?

[@alevelbiologymrashcroft8177]

Hi. The cells will look 100x magnified from actual size with a 10x objective lens (as the objective lens is 10x and the eyepiece lens is 10x), but ALSO so will the stage micrometer and it is this you are using to calibrate the eye piece graticule that you can see down the microscope. So you do not have to worry about any other division. Same goes for the 40x objective (the cell is magnified 400x in total here) but the stage micrometer is also magnified by the same amount, so you use this to recalibrate the eye piece graticule. The cells and the stage micrometer will both look 4x bigger if you flip from 10x to 40x objective lens but the eye piece graticule always looks the same as it is in the eye piece not the objective lens that has changed. Hope that helps.

[@boeradley223]

YOU'RE THE BEST MAY GOD BLESS YOU

[@ilikebands6666]

Thank you for this video! Helps a lot!

[@qazizahor7080]

Excellent vid

[@poggom]

is the.eye piece unit same for all microscopes or am I just dumb?

[@alevelbiologymrashcroft8177]

Hey. In this example the eye piece graticule has 100 small divisions but the graticule says 0-10. It's the small divisions you are interested in. Some other eye piece graticules have 0-100 written on them but they are both exactly the same length. Think of a ruler 10cm long but another ruler 100mm long. Same length ruler. Hope that helps.

[@izharullah9781]

Sir i am still confused that how to find the diameter of field of view for OPTIKA microscope. please would you like to guide me sir..

[@alevelbiologymrashcroft8177]

Place the stage micrometer under the objective lens. Focus. Count how many stage micrometer divisions fit across the circular field of view (= diameter). The stage micrometer scale always has a specific length divided by 100 divisions. Use this to work out one division. E.g scale is 1mm in length divided by 100 divisions, so 1 division is 0.01mm (10um). Multiply by the number of divisions you counted across diameter = diameter now in um. Then use this to work out radius and then use this for area of a circle (pi x r^2), which is the area of your field of view.

[@hanyabdulla8113]

Thanks 🙏

[@zhanettabayanbekova]

thank you!

[@annabelle466]

Hold on, surely 1 s.m.u is equal to 0.01mm because the small divisions on a stage micrometer have gaps equal to 0.01mm?

[@alevelbiologymrashcroft8177]

queen atastic depends on the stage micrometer being used. There are 2 types: first type is when the stage micrometer scale is 10mm long divided by 100 units (so each stage micrometer unit equals 10mm divided by 100 = 0.1mm.. or 100um); the second type is when the stage micrometer scale is 1mm long divided by 100 units (so each stage micrometer unit equals 1mm divided by 100 units = 0.01mm... or 10um). Here we have used the first one not the second one. The length of the stage micrometer and what each unit is worth is written on the black stage micrometer slide you are using. Have a look at the slide in the video. You might well use the second type of stage micrometer in your school/college etc..

[@annabelle466]

A Level Biology: Mr Ashcroft thank you! This has cleared things up for me 😀

[@annabelle466]

A Level Biology: Mr Ashcroft what would happen if the stage micrometer only has 10 bigger divisions?

[@alevelbiologymrashcroft8177]

queen atastic have never seen that but... the purpose of the stage micrometer is that you know the length of each division so as long as you can overlap a certain number of eye piece graticule units with that then you can work out a single eye piece graticule unit. Then just measure the width of the cell, or whatever structure you want, in e.p.u and multiply this by what each e.p.u is worth... e.g if the stage micrometer was 1mm long and only divided into ten units.. each of these units would be 0.1mm.. if 40 e.p.u overlapped this then 1e.p.u would be 0.1mm divided by 40..

[@annabelle466]

A Level Biology: Mr Ashcroft ok! Got you! Thanks so much again

[@mayaszymecka2007]

i get it now omg

[@steveanderson5871]

Why is the epu 40 and not 4, because it’s from 1-10

[@alevelbiologymrashcroft8177]

It's the small divisions.. so on the eye piece graticule it is actually 40... So 1 would have 10 smaller epu divisions, 2 would have 20 divisions etc..

[@Salonisharma1204]

💌🔥🔥🔥🔥❣️