From
mm²Square Millimeter
The square millimetre equals 1/1,000,000 of a square metre. Used in precision engineering, electronics (transistor size, chip area) and microscopy. The cross-section of an electrical cable is often specified in mm².
Real-world: Typical household wiring is 2.5 mm² copper. A grain of rice covers about 10 mm². A pin head is under 1 mm².
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