Electricity
The Free High School Science Texts: A Textbook for High School Students Studying Physics
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Flow of Charge - Circuits - Voltage and Current - Resistance - Voltage and Current in a Practical Circuit - How Voltage, Current, and Resistance Relate - Ohm's Law Analogy - Power in Electric Circuits - Calculating Electric Power - Resistors - Nonlinear Conduction - Circuit Wiring - Polarity of Voltage Drops - Series and Parallel - Simple Series Circuits - Simple Parallel Circuits - Power Calculations - Using Ohm's Law - Conductor Size - Fuses - Important Equations and Quantities

Conductor Size

It should be common-sense knowledge that liquids flow through large-diameter pipes easier than they do through small-diameter pipes (if you would like a practical illustration, try drinking a liquid through straws of different diameters). The same general principle holds for the flow of electrons through conductors: the broader the cross-sectional area (thickness) of the conductor, the more room for electrons to flow, and consequently, the easier it is for flow to occur (less resistance).

Electrical wire is usually round in cross-section (although there are some unique exceptions to this rule), and comes in two basic varieties: solid and stranded. Solid copper wire is just as it sounds: a single, solid strand of copper the whole length of the wire. Stranded wire is composed of smaller strands of solid copper wire twisted together to form a single, larger conductor. The greatest benefit of stranded wire is its mechanical flexibility, being able to withstand repeated bending and twisting much better than solid copper (which tends to fatigue and break after time).