Eureka:
- Constantan is a Nickel-Copper alloy also known as Eureka.
- It usually consists of 55% copper and 45% nickel.
- Its main feature is the low thermal variation of its resistivity, which is constant over a wide range of temperatures
- Constantan is a Nickel-Copper-based alloy wire that has a high resistivity and is mainly used for thermocouples and electrical resistance heating.
- It has a constant resistivity over a wide range of temperatures.
Composition:
- Ni = 45 %
- Cu = 55 %
Properties of Eureka:
- Resistivity - 490 µΩ -cm
- Melting point: 1300 ⁰C
- Specific gravity: 8.9 gm /cm3
- Negligible temperature Coefficient
- Easily ductile
- Resistant to atmospheric corrosion
- Can be easily soldered and moulded
Application:
- It is used for the measurement of temperature.
- It is used for the formation of thermocouple, along with the wires of other metals such as copper, iron, and chromium.
- It is especially used for resistance purposes since its resistance does not change much with the change in its temperature. It is used for DC current shunts.


