ANS:D - constanton

Constantan is an alloy composed mainly of copper and nickel, typically containing around 55% copper and 45% nickel. It is known for its stable electrical resistance over a wide range of temperatures, low thermal expansion coefficient, and high resistance to corrosion. The name "constantan" is derived from its ability to maintain a nearly constant resistance despite changes in temperature. Here are some key properties and applications of constantan:

1. Electrical Resistance: Constantan has a relatively high electrical resistance compared to pure copper. This property makes it suitable for use in resistors, where precise and stable resistance values are required.
2. Temperature Stability: Constantan exhibits stable electrical resistance over a wide temperature range, making it useful in applications such as thermocouples and temperature sensors.
3. Thermal Expansion: Constantan has a low coefficient of thermal expansion, meaning it expands and contracts minimally with changes in temperature. This property contributes to its dimensional stability and makes it suitable for applications where thermal expansion needs to be minimized.
4. Corrosion Resistance: Constantan is resistant to corrosion, which extends its lifespan and makes it suitable for use in harsh environments.
5. Applications: Constantan is commonly used in various electronic and electrical applications, including resistors, strain gauges, thermocouples, heating elements, and temperature sensors.