What alloy is commonly selected for electric heating coils and resistance elements____________________?
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Answer: A. nichrome
Explanation
Nichrome possesses exceptionally high electrical resistance properties which generate heat efficiently. The inclusion of chromium provides superior oxidation resistance at elevated operational temperatures. These combined metallurgical traits prevent the heating element from burning out quickly. Nichrome is a non-magnetic alloy typically composed of approximately eighty percent nickel and chromium. It maintains its structural integrity and high electrical resistivity when heated red-hot. Electric current passing through the wire encounters resistance, converting electrical energy into heat.
Toasters, hair dryers, and industrial furnaces rely on nichrome wire for reliable heating. Heating elements must withstand thermal expansion and contraction without fracturing during use. This alloy ensures long-lasting performance in domestic and commercial heating appliances. Invar is chosen for its extremely low coefficient of thermal expansion in precision instruments. Manganin is primarily utilized for precision electrical resistors due to its stable resistance. Elinvar maintains a nearly constant modulus of elasticity across varying ambient temperatures.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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