Slide 1

E STIMATING THE S IZE OF C ELLS Slide 2 T HE M ETRIC S YSTEM measurement system based on the number ten can be used to measure length (m), volume (L), mass (g), energy (J) Slide 3 C ONVERTING IN THE M ETRIC S YSTEM converting from millimetres to micrometers multiply by 1000 4.5 mm = m converting micrometers to millimetres multiply by 1000 0.673 m = Slide 4 S TEPS FOR D ETERMINING F IELD OF V IEW ON L OW P OWER 1. On low power, place a transparent millimetre ruler on the stage. 2. Focus the marks on the ruler using the coarse and fine adjustment knobs. 3. Move the ruler so one of the marks is at the edge of the field of view. 4. Record the diameter of the field of view for low power. Slide 5 S TEPS FOR D ETERMINING F IELD OF V IEW ON L OW P OWER Slide 6 S TEPS FOR D ETERMINING F IELD OF V IEW ON M EDIUM AND H IGH P OWER 1. Use the following equations to calculate the diameter of the field of view: a. diameter of medium power diameter = total low power magnification X diameter low power total medium power magnification b. diameter of high power diameter = total low power magnification X diameter low power total high power magnification Slide 7 F IELD OF V IEW - E XAMPLES LensMagnificatio n Eyepiece Magnification Total Magnification Diameter (mm) Low Medium High Slide 8 S TEPS FOR E STIMATING THE S IZE OF C ELLS 1. Estimate the number of cells that would fit along the diameter of the field of view. 2. Use the following equation to calculate the estimated size of the cell: size of cell = diameter of field of view number of times cell would fit along diameter Slide 9 S IZE OF C ELLS - E XAMPLES Low Power High Power