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The electrical resistivities of a few ma...

The electrical resistivities of a few materials are given in ohm.metre. Which of these materials can be used for making an element of a heating device ?
(A) `6.84 xx 10^-8`
(B) `1.60 xx 10^-8`
( C) `1.00 xx 10^-4`
(D) `2.50 xx 10^12`
( E) `4.40 xx 10^-5`
(F) `2.30 xx 10^17`.

Text Solution

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For making the element of a heating device, we use an alloy as :
(i) its resistivity changes less rapidly with changes in temperature and
(ii) it does not oxidise (burn) readily at high temperature. The resistivities of materials `C and E` lie in the range of resistivity of alloys. (In fact, material `C` is nichrome and material `E` is manganin. We use nichrome for making an element of a heating device).
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