Total Magnification and Unit Conversions


You will notice each objective lens is labelled on your microscope.
The lenses are commonly labelled 10x, 40x, and 100x, but each microscope is different. These labels tell you by how much the objective lens is magnifying the object. The ocular lens is also magnifying the object by 10x. This means you must multiply the objective lens magnification by the ocular lens magnification to get the true magnification of the object. For example, if you are looking through the 10x objective lens, you must multiple 10x by the 10x magnification of the ocular lens: 10 x 10 = 100x. The true magnification of the object is 100x!

Magnification also deals with a fair amount of unit conversion. You have learned about converting from one unit to another in your previous math courses, but here is a short review.

A3.5 Objective lenses labeled 50x and 20x

Example:


A specimen on a slide is 0.02 millimetres ( «math xmlns=¨http://www.w3.org/1998/Math/MathML¨» «mi»mm«/mi» «/math») long. How long is the specimen in micrometres ( «math xmlns=¨http://www.w3.org/1998/Math/MathML¨» «mi»§#956;m«/mi» «/math»)?

 


Step 1: How many μm are in 1 space mm?

Use the conversion chart in your data booklet to look up how many µm are in one mm. There are 1 space 000 space μmin 1 space mm.

Step 2: Cross multiply and divide to solve for «math xmlns=¨http://www.w3.org/1998/Math/MathML¨» «mi»X«/mi» «/math».


«math xmlns=¨http://www.w3.org/1998/Math/MathML¨» «mn»0«/mn» «mo».«/mo» «mn»02«/mn» «mo»§#215;«/mo» «mn»1«/mn» «mo»§#160;«/mo» «mn»000«/mn» «mo»=«/mo» «mn»20«/mn» «/math»
Step 3: Then divide by what is left over.
«math xmlns=¨http://www.w3.org/1998/Math/MathML¨» «mfrac» «mrow» «mi»X«/mi» «mo»§#160;«/mo» «mi»§#956;m«/mi» «/mrow» «mrow» «mn»0«/mn» «mo».«/mo» «mn»02«/mn» «mo»§#160;«/mo» «mi»mm«/mi» «/mrow» «/mfrac» «mo»=«/mo» «mfrac» «mrow» «mn»1000«/mn» «mo»§#160;«/mo» «mi»§#956;m«/mi» «/mrow» «menclose notation=¨circle¨ mathcolor=¨#EB6D2E¨» «mn mathcolor=¨#191919¨»1«/mn» «mo mathcolor=¨#191919¨»§#160;«/mo» «mi mathcolor=¨#191919¨»mm«/mi» «/menclose» «/mfrac» «/math»
 
«math xmlns=¨http://www.w3.org/1998/Math/MathML¨» «mn»20«/mn» «mo»§#247;«/mo» «mn»1«/mn» «mo»=«/mo» «mn»20«/mn» «mo»§#160;«/mo» «mi»§#956;m«/mi» «/math»

«math xmlns=¨http://www.w3.org/1998/Math/MathML¨» «mn»0«/mn» «mo».«/mo» «mn»02«/mn» «mo»§#160;«/mo» «mi»mm«/mi» «/math» is equal to «math xmlns=¨http://www.w3.org/1998/Math/MathML¨» «mn»20«/mn» «mo»§#160;«/mo» «mi»§#956;m«/mi» «/math».

  Watch This

Unit Conversions


These videos will take you through the steps on how to perform basic unit conversions. This may be review for you, or this may be new information. These videos move fairly fast and use units you may not see in Science 10. This is OK, as a conversion works the same for any unit! If you have any questions, please ask your teacher for help.