In hot wire instrument, the sensing wire is made of
A. Copper
B. Silver
C. Platinum-iridium
D. Copper-Nickel
Show Answer
Answer: C
Explanation:-
These instruments utilize the principle of expansion of wire, heat due to the current being measured, passing through the wire.
It consists of a hot wire of platinum-iridium (because it can withstand high temperatures of about 300°C without being oxidized), and about 0.2 mm in diameter.
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