Converting Between Units: Extended
Extended Tier Only
- The size of cellular structures is often given in micrometres (μm), while rulers are usually used to measure the size of objects in millimetres (mm)
- The conversion between µm and mm is:
1 mm = 1000 µm
- The discrepancy between cellular size and the measurements that can be gained using a ruler means that calculations will sometimes require conversion between μm and mm, or vice versa
Unit conversions table
Converting mm to μm diagram
Worked example
Step 1: convert the units so that they match
1 mm = 1000 µm
The actual thickness of the leaf is given as 2000 µm
To convert 2000 µm into mm we divide this number by 1000
2000 ÷ 1000 = 2
The actual thickness of the leaf in mm is 2 mm
Step 2: enter numbers into the magnification equation
magnification = image size ÷ actual size
50 ÷ 2 = 25
So the magnification is x25
Examiner Tip
Unit conversion is the most common source of error in questions that include magnification calculations, so don't forget to do this, and make sure that you are confident converting µm into mm or mm into µm.
