measuring microscopic things - information sheetmyscope-explore.org/sideactivities/measuring... ·...
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![Page 1: Measuring microscopic things - Information Sheetmyscope-explore.org/sideActivities/Measuring... · scale seen using a scanning electron microscope at high magnification. The bar on](https://reader036.vdocuments.net/reader036/viewer/2022070719/5edf8a76ad6a402d666ae11a/html5/thumbnails/1.jpg)
Sometimesitisusefultoknowtherealsizeorlengthofanobject.Ineverydaylifewecangetoutarulerandmeasureitdirectly.Thesizecanthenberecordedeitherasmeters,centimetersormillimeters,orasfeetandinches.
MicrometersOncetheobjectgetstobeverysmallthough,itisnecessarytomovetoadifferentkindofmeasurement.Insteadofmillimeterswemeasureinthousandsofamillimeter.Suchatinydivisioniscalledamicrometer.Itisgivenaspecialsymbol:µ,meaningmicro.Sowhen1µmisseen,wereadthisasonemicrometer.
NanometersTherearesmallermeasurestoo.Justlikethereare1000µmin1mm,thereare1000nanometers(nm)in1µm.Whenwewanttomeasurethesizeofanobjectshowninamicrograph(photographtakenusingamicroscope),wehavetorelyonthebarshownatthebottomoftheimage.Findthewhitebarsinthemicrographswithanumberattheend.Thecoloredimageisofabutterflywingseenthroughalightmicroscope.Noticethatthebarreads1mm.Thegreyimageisofonewingscaleseenusingascanningelectronmicroscopeathighmagnification.Thebaronthisimagereads1µm.CalculatingsizeTocalculatetherealsizeofthewingscalesinthetopimageweeithermeasureitonscreenoritmightbeeasiertoprintoutthissheet.Firstmeasurethelengthofthewhitebar(ontheprintedpage).Thiscomestoabout43.5mmdependingonyourprinter.Next,notethereallengthofthewhitebar,whichis1mm(thenumbernexttothewhitebar).Then,measurethewidthofaloosewingscale.Thiscomestoabout1.9mm(ontheprintedpage)again,dependingonyourprinter.
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Nowcomesthepartwhereweworkouthowwidethatwingscalereallyisintherealworld.Multiplythewidthofthewingscaleinmillimeters(1.9mmorwhateveryoumeasure)bythesizethebartellsusisitsreallength(1mm).Dividetheanswerbythelengthofthebarinmillimeters(43.5mmorwhateveryoumeasure)togettherealwidthofthewingscale:
(1.9x1)/43.5=0.044mm.Ifwemultiplythisnumberby1000,itgivesusthesizeinmicrometers:
44µmTrythismethodwiththeSEMmicrographofabutterflywingscaleinthebottomimage.Calculatehowfarapartthelongridgesareonasinglebutterflyscale.Sincethebarisabout11mmlongontheprintedimage,andthisequalsarealworldlengthof1µm,andtheridgesareabout17.5mmapartontheprintedimage,theanswershouldbethattheridgesarereally1.59µmapart.Notethatthebarisusuallyreferredtoasascalebar,meaningthatitscalesupordowndependingonwhetherapictureisenlargedorreducedinsize,alwaysremainingaccurate.Inthiscontexttheword‘scale’hasnothingtodowithwingorfishscales.YouhaveagoHereisanotherexamplethatisnotworkedthrough.Calculatetherealsizeofthispollengrainfromyellowclover,intheSEMmicrographbelow.Youshouldgetananswerinmicrometers.Howmanyofthesepollengrainswouldfitintoasinglemillimeter?InternetresourcesThisisavideothatshowshowtocalculaterealsizefromanimageusingthebar:https://www.youtube.com/watch?v=5h5IFY-PYRw