BIOL 2020 Lecture Notes - Lecture 7: Weighted Arithmetic Mean, Power3, Coulter Counter
20 Apr 2020
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Weight average will show that more larger particles present: w/regular lab microscope we can measure large particles 1-1000 micron, electrons can measure nanometers, 2 ways we can measure projected diameter: perimeter diameter (dp) & area diameter (da) Dp will give larger particle size since circle; da more accurate but requires software to calculate. Microscope methods gives us number and size. But then it counts 200 particles total to make an average. We could how many particles within a range of diameters. Then calculate number and multiple by diameter and total number of particles. Microscopic data can be converted to weight average diameter. Number average emphases smaller particles more; weight average emphasizes larger size more. So average diameter for weight based is bigger than number based. 3. coulter counter (electric stream sensing: 0. 1-1000um, volume diameter, volume average diameter, advantages: directly measures particle volume & measurement irrespective of shape.
