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GCE CIE Biology - Magnification and Measurement Units

Chapter 1 Cell Structure

· biology,GCE CIE,magnifications,microscope,measurement units

1.1.b Calculate the linear magnifications of drawings, photomicrographs and electron micrographs

1.1.c Use an eyepiece graticule and stage micrometer scale to measure cells and be familiar with units (millimetre, micrometre, nanometre) used in cell studies

For GCE CIE Biology, it is important to remember the relevant units of measurement used in cell studies (as equivalent in meters) :

- 1 Millimeter (
**mm**) =**10**^{-3}**of a meter** - 1 Micrometer (
**μm**) =**10**^{-6 }**of a meter** - 1 Nanometer (
**nm**) =**10**^{-9 }**of a meter**

⚠️📝*Remember: to convert mm to μm, or μm to nm, just divide by 1000!*

**EYEPIECE GRATICULE AND STAGE MICROMETER IN MICROSCOPY**🔬:

- Eyepieces of a microscope have a little scale called the
**eyepiece graticule**which is used to measure objects. - The eyepiece graticule usually has 100 divisions.
- A
**stage micrometer**is used to*calibrate*the eyepiece graticule into real life sizes. - Normally, the scale is found on a microscopy glass slide.

As you can see from the image above, the stage micrometer is being used for calibrating the eyepiece graticule scale.

**CALCULATING LINEAR MAGNIFICATIONS **🔎:

The formula to calculate magnification is:

**Magnification (M)= Image Size with Ruler (I) ÷ Actual size (A)**

⚠️📝*Remembering this triangle/formula will come in handy for your **GCE CIE Biology** exam, especially when doing other calculations (i.e., finding the actual size of the object) . *

Yes! All done! Catch you later! 👏

References:

- Jones, M., & Parkin, M. (2018).
*Cambridge International As and A level biology*. Cambridge: Cambridge University Press. - Linear Magnification. (2013, March 25). Retrieved from http://jessbiologyrevision.blogspot.com/2013/03/linear-magnification.html
Toole, G., & Toole, S. (2017).

*Biology in Context for Cambridge International As & A level*. Oxford: Oxford University Press.

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