Diameter is the distance across a circle. Area is how much room is inside it. They do not grow at the same rate.
Conductor size is about area, not width. Thinking a wire twice as wide carries twice as much is the intuition this lesson exists to break.
The radius is half the diameter, and the formula squares it. So doubling the diameter doubles the radius, and squaring a doubled number multiplies it by four. Twice as wide is four times the area -- not twice.
Check yourself: You double a conductor's diameter. What happens to its circular area?
Answer: It becomes four times larger.
Area depends on the radius squared. Double the radius and you square that doubling: 2 x 2 = 4.
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Written from the owner's poster for this lesson. Nothing added beyond what the poster states.
Written for Texas apprentices as free study material. The Texas apprentice licence is an application, not an exam (Occupations Code 1305.161), and nothing here counts as apprenticeship hours or continuing-education credit. VoltMark is not affiliated with, endorsed by, or sponsored by NFPA, PSI, TDLR, or any state or local licensing authority. Always follow your employer's safety programme and your supervising electrician.
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