IB Biology HL 1Mrs. PetersFall 2013

Magnification

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

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 = 10mm2. Convert mm to µm; 10,000 µm3. 10,000/2 = 5,000 µmPractice calculating magnification!!

How to calculate actual size 1. Measure the dimension of

the object in mm2. Divide the measurement by

the magnification3. Convert to appropriate units

(usually same as scale bar)Ex: Determine the length of

the vacuole.1. Vacuole length = 50 mm2. 50/5,000 = .01 mm3. .01mm = 10 µmThe length of the vacuole is 10

µm.Practice calculating actual

size!!

Magnification

magnification = size of image

magnification

Then convert to correct units!