Why are alloys used for making standard resistance coils?

Standard resistance coils are formed from alloys having a high resistivity value and a low-temperature coefficient of resistivity.

• The temperature coefficient of resistivity of a resistance coil should be modest. That means the resistance of certain materials will not change a lot with a change in the temperature.
• If the resistivity of a material is high, its resistance increases. Therefore, high resistivity materials should be used to make a resistance coil for more standard resistance.
• Alloys like manganin and constantan are examples of materials with high resistivity, a modest temperature coefficient. They are largely unaffected by environmental influences such as air, temperature, and moisture.
• Therefore, alloys are used to produce conventional resistance coils.

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