Explain the following (a) Copper and aluminium wires are usually employed for electricity transmission. Explain the reason (b) Explain how the resistance of a wire varies with its length. (c) The tungsten is used almost exclusively for filament of electric lamps.
Solution
a)Copper and aluminum are good conductors of electricity also they have low resistivity. So they are usually used for electricity transmission. b)Resistance (R) of a wire is inversely proportional to its area of cross-section (A), i.e, when area of cross section increases the resistance decreases. c) The melting point of tungsten, which is a metal, has a very high melting point and very high resistivity so does not burn easily at a high temperature.
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