1. IB Biology HL 1 Mrs. Peters Fall 2013 Magnification

2. Important Magnification Terms Magnification: the ratio of the size of the image to the size of the object. Scale Bar: a short line usually drawn on a micrograph to show the magnification. Units: most scale bars are measured in micrometers (µm) You will make measurements in millimeters (mm) mm = 10 -3 ; µm = 10 -6 Converting will be moving the decimal 3 place left or right Scale Bar

3. How to calculate magnification of a micrograph 1. Measure the scale bar in mm 2. Convert mm to same unit as scale bar (convert mm to µm) 3. Divide converted measurement by scale bar This gives you the magnification of the micrograph Ex: Determine the magnification of the plant cell. 1. Scale bar = 10mm 2. Convert mm to µm; 10,000 µm 3. 10,000/2 = 5,000 µm Practice calculating magnification!!

4. How to calculate actual size 1. Measure the dimension of the object in mm 2. Divide the measurement by the magnification 3. Convert to appropriate units (usually same as scale bar) Ex: Determine the length of the vacuole. 1. Vacuole length = 50 mm 2. 50/5,000 =.01 mm 3..01mm = 10 µm The length of the vacuole is 10 µm. Practice calculating actual size!!

5. Magnification magnification = size of image magnification Then convert to correct units!