Physics · 12

Resistance and Resistivity

Resistance is the property of a material that opposes the flow of electric current. Resistivity is an intrinsic property of the material itself. Toget

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Why do we use thick wires for high-current circuits?

Thick wires have larger cross-sectional area (A), which decreases resistance (R = ρL/A). Lower resistance means less power loss as heat and safer operation.

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What is the difference between a conductor, semiconductor, and insulator?

Conductors (like copper) have low resistivity (~10^-8 Ω m), semiconductors (like silicon) have intermediate resistivity (~10^3 Ω m), and insulators (like rubber) have very high resistivity (~10^15 Ω m or more).

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Why does a copper wire get hot when carrying current?

When current flows through copper, electrons collide with atoms, losing kinetic energy which converts to heat. The power dissipated is P = I^2R, proportional to the square of current.

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