Question

Constantan is an alloy of
1. Platinum and radium
2. Copper and nickel
3. Copper and tin
4. Silver and gold

Answer 1

Correct Answer - Option 2 : Copper and nickel

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 temperature.

Composition:

• Cu = 55%
• Ni = 45%

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.