Eyepiece graticule and stage micrometer A level Biology - BioTeach
Summary
TLDRThis video from BioTeach explains how to calibrate microscopes using an eyepiece graticule, a tool crucial for A-Level biology students studying cells. The graticule, placed in the eyepiece, is calibrated against a stage micrometer to measure objects under the microscope. The tutorial walks through aligning the graticule with the stage micrometer, calculating the size of each division, and applying this calibration to measure cell sizes accurately. The video is a practical guide for lab practice, emphasizing the need for recalibration with different magnifications or microscopes.
Takeaways
- 🔬 The video focuses on how to calibrate microscopes using the eyepiece graticule, essential for A-Level biology students.
- 📏 The eyepiece graticule is used to measure the size of objects under a microscope and is typically 1 millimeter long, divided into 100 units.
- 🧪 A stage micrometer, also 1 millimeter long and divided into 100 divisions, is used to calibrate the eyepiece graticule.
- 🔧 To calibrate the microscope, the eyepiece graticule must be aligned with the stage micrometer.
- 📊 Once aligned, the number of divisions on the eyepiece graticule that correspond to stage micrometer divisions must be counted.
- 📐 The video explains a calculation where 10 stage micrometer divisions correspond to 21 eyepiece graticule divisions.
- 🎯 The size of each division on the eyepiece graticule can be calculated by dividing the micrometer measurement by the number of divisions.
- 🧬 After calibration, measurements in micrometers can be made on the sample, such as determining the size of cheek cells.
- 🔄 The eyepiece graticule must be recalibrated for each magnification or when using a different microscope.
- 📚 The video teases an upcoming comparison of optical and electron microscopes, including past exam questions.
Q & A
What is the main topic of the video?
-The main topic of the video is how to calibrate microscopes using the eyepiece graticule, which is relevant for A-level biology students studying cells.
What is a graticule used for in microscopy?
-A graticule is used to measure the size of an object viewed under a microscope. It is placed in the eyepiece of the microscope and is often about one millimeter long, divided into 100 equal units.
What is the purpose of a stage micrometer in microscopy?
-A stage micrometer is a slide with a scale that is exactly one millimeter long, divided into 100 divisions. It is used in combination with a graticule to calibrate the microscope so that a precise scale can be calculated at each magnification.
How does the calibration process of the eyepiece graticule work?
-The calibration process involves aligning the eyepiece graticule with the stage micrometer, counting how many divisions on the graticule correspond to a set of stage micrometer divisions, and then calculating the size of one division on the graticule based on the known size of the stage micrometer divisions.
Why is it necessary to recalibrate the eyepiece graticule for different magnifications?
-It is necessary to recalibrate the eyepiece graticule for different magnifications because the scale of the graticule changes with the magnification, and the calibration ensures accurate measurements of the specimen.
What is the significance of the 100 divisions on the stage micrometer?
-The 100 divisions on the stage micrometer are significant because each division represents 0.01 millimeters, allowing for precise measurement when calibrated with the eyepiece graticule.
How can you remind yourself of the alignment between the eyepiece graticule and the stage micrometer while looking through the microscope?
-You can rotate the eyepiece slightly to remind yourself of the alignment between the eyepiece graticule and the stage micrometer, as it can be confusing to remember which is which when looking through the microscope.
What is the conversion factor from millimeters to micrometers?
-The conversion factor from millimeters to micrometers is 1000, as 1 millimeter is equal to 1000 micrometers.
What is the importance of knowing the magnification when measuring cells under a microscope?
-Knowing the magnification is important because it allows you to convert the number of divisions counted on the eyepiece graticule into an actual length, providing accurate measurements of the specimen.
Why is it necessary to recalibrate the eyepiece graticule when using a different microscope?
-It is necessary to recalibrate the eyepiece graticule when using a different microscope because the magnification and scale may vary between microscopes, and recalibration ensures accurate measurements.
What is the next topic that will be covered in the series of videos?
-The next video will be based on the types of microscopes, comparing optical microscopes to electron microscopes, and it will also cover some past paper questions related to microscopy.
Outlines
🔬 Microscope Calibration Using Eyepiece Graticule
This video by Bioteach educates viewers on the calibration of microscopes using an eyepiece graticule, a vital skill for A-level biology students studying cells. The graticule, placed in the microscope's eyepiece, is typically one millimeter long and divided into 100 units. It is used in conjunction with a stage micrometer, a slide with a precise one-millimeter scale, to measure the size of objects under the microscope. The video demonstrates the calibration process, which involves aligning the graticule with the stage micrometer and calculating the size of each graticule division based on the stage micrometer's divisions. The example provided shows that 10 divisions on the stage micrometer correspond to 21 divisions on the eyepiece graticule, leading to the calculation that one division on the eyepiece graticule is 4.8 micrometers. The video emphasizes the necessity of recalibrating the graticule for each microscope and magnification used, ensuring accurate cell measurements.
👋 Acknowledgment of Viewer
The second paragraph is a brief acknowledgment of the viewer, likely a direct address to the audience, possibly indicating a transition or a pause in the video. The content is minimal, consisting only of the word 'you,' suggesting a personal touch or a moment of engagement with the viewers.
Mindmap
Keywords
💡Eyepiece Graticule
💡Stage Micrometer
💡Calibration
💡Magnification
💡Micrometers
💡Hemocytometer
💡Division
💡Cheek Cells
💡Optical Microscope
💡Cells
Highlights
Introduction to calibrating microscopes using the eyepiece graticule for A-level biology students.
Explanation of the necessity of precise measuring equipment for microscopic observations.
Description of the graticule and its placement in the eyepiece of a microscope.
Introduction to the stage micrometer and its role in calibrating the graticule.
Demonstration of aligning the eyepiece graticule with the stage micrometer.
Instruction on counting divisions on the graticule corresponding to stage micrometer divisions.
Guidance on identifying the scale of the stage micrometer for calibration purposes.
Calculation of the size of one division on the eyepiece graticule.
Conversion of measurements from millimeters to micrometers for practical use.
Procedure for measuring a specimen using the calibrated eyepiece graticule.
Example calculation of the size of a cheek cell using the calibrated graticule.
Emphasis on recalibrating the graticule for each microscope and magnification used.
Upcoming video teaser on types of microscopes and comparison with electron microscopes.
Encouragement for viewers to ask questions in the comments section for further clarification.
Conclusion and sign-off, thanking viewers for watching the video.
Transcripts
[Laughter]
hi everyone and welcome to another video
by bioteach
this time focusing on how we calibrate
microscopes using the eyepiece graticule
this video is relevant for a-level
biology for the cells topic
you will hopefully get a chance to use
the microscopes in the lab
and will get a chance to practice how to
measure cells
measuring and counting objects to be
viewed under a microscope
requires precisely marked measuring
equipment two commonly placed
pieces of equipment are the graticule
and the hemocytometer
this video is focusing on the graticule
which is used to measure the size of an
object
a graticule is placed in the eyepiece of
a microscope and sometimes these are
called eyepiece microphones
or eyepiece graticules it's usually
about one millimeter long
divided into 100 equal units
a graticule is used in combination with
a stage micrometer
to work out the size of the object being
viewed
the stage micrometer is a slide with a
scale that's exactly one millimeter long
and is also divided into 100 divisions
which means each division is 0.01
millimeters
this is placed on the stage of the
microscope the stage micrometer
allows the graticule to be calibrated so
that a precise scale can be calculated
at each magnification of the microscope
this image here shows you the microscope
with an eyepiece location
and the example of the stage micrometer
there are various steps you have to
complete to be able to calibrate your
eyepiece graticule
the first step is to align the eyepiece
graticule with the stage micrometer
once they're on top of each other you
need to be able to count how many
divisions on the eyepiece graticule
correspond to a set of stage micrometer
divisions
at this stage you might forget which one
is which when you're looking down the
microscope
so you could rotate the eyepiece a
little to remind yourself if you need to
in this example my stage is the scale in
red
and the eyepiece as the scale in blue
and i can see that every 10 stage
micrometer
divisions are around 21 ip squareticule
divisions
the next step is to calculate how big
one division
is on the eyepiece for this we need to
know how long
every small division is on the stage
micrometer so you can check the size of
your micrometer by looking at the label
on the site itself
if it is one millimeter long in total
then every 10
small divisions is not 0.1 millimeters
long
and every small division is not .01
millimeters long
this scale here shows you a bit more of
a close-up if you struggle to picture it
from the previous slide
we have said that 10 micrometer
divisions were 21
ip's graticule divisions and i've set
this up a bit like ratios so we can
easily work
out what each division is so if
10 micrometer divisions were 21 ip's
graticule divisions
and we know that 10 was 0.1 millimeters
long
then we know that 1 must be 0.1 divided
by 21
which is 0.0048 millimeters to 2
sig fig now we don't want to work with
these inconvenient decimal places
they're quite ugly numbers to work with
and so we can convert this to
micrometers by multiplying by a thousand
so 0.048
becomes 4.8 micrometers
essentially what we're saying is that
each division
is 4.8 micrometers so now we're in a
position
to be able to measure the sample at
magnification
you can measure your specimen using the
eyepiece micrometer
and convert the number of eyepiece
micrometer divisions you have counted to
an actual
length so if i'm looking at some cheek
cells as you can see
on your video now i can see that the
length of one cheek cell is around 16
units long
on the eyepiece graticule i now know
that one
eyepiece micrometer division is 4.8
micrometers long
so this cell must be 16 times 4.8 which
means
76 76.8 micrometers long
don't forget that you have to calibrate
the eyepiece graticule for every
magnification you use
and you also have to recalibrate it if
you use it for a different microscope
i hope that's been super useful for you
i know it's a short video
but if you follow those steps the next
time you have a microscopy lesson
you should be able to calibrate your
microscope with ease
so that's all i have for you on this
particular subject
my next video is based on the types of
microscopes where i'll be comparing the
optical microscopes
to the electron microscopes and it will
also cover
some past paper questions as a part of
that thank you so much for watching
as always if you have any questions
about this topic please leave me a
comment below this video
and i'll get back to you as soon as i
can bye for now
you
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