Which of the following is universally employed as the low expansion metal in the bimetallic thermometer, which is an iron-nickel alloy containing 36% nickel and has very low co-efficient of expansion (1/20th of ordinary metals) ?
Correct answer: A
Explanation
Invar is an iron-nickel alloy known for its very low coefficient of thermal expansion, making it suitable for bimetallic thermometers.