Uploaded July 2023 | Updated September 2026, 1 hour ago

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You can find all my A Level Biology videos fully indexed at freesciencelessons.co.uk/a-level-revision-videos/a-level-biology

In this video, we look at calculations involving magnification. First we explore how to determine the size of organelles from a microscope image using a scale bar. We then look at how we can use an equation to determine the magnification of an image and how to determine the actual size of an organelle.

Image credits:

Pancreatic Acinar Cell
commons.wikimedia.org/wiki/File:Pancreatic_acinar_cells_-_TEM.jpg
Louisa Howard, Public domain, via Wikimedia Commons

Bluetongue virus cell
commons.wikimedia.org/wiki/File:CSIRO_ScienceImage_1899_Viral_Structure_of_the_Bluetongue_Virus.jpg
CSIRO, CC BY 3.0 creativecommons.org/licenses/by/3.0, via Wikimedia Commons

Macrophage in alveolus
commons.wikimedia.org/wiki/File:Macrophage_in_the_alveolus_Lung_-_TEM.jpg
Louisa Howard, Public domain, via Wikimedia Commons

Cell nucleus
commons.wikimedia.org/wiki/File:Micrograph_of_a_cell_nucleus.png
This file has been identified as being free of known restrictions under copyright law, including all related and neighbouring rights.

Golgi apparatus
commons.wikimedia.org/wiki/File:Human_leukocyte,_showing_golgi_-_TEM.jpg
Louisa Howard, Public domain, via Wikimedia Commons

Green ruler
commons.wikimedia.org/wiki/File:Righello1.jpg
Luigi Chiesa, CC BY-SA 3.0 creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons

Light microscope
commons.wikimedia.org/wiki/File:Optical_microscope_nikon_alphaphot.jpg
GcG(jawp), Public domain, via Wikimedia Commons