InterviewSolution
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InterviewSolution
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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`. |
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Answer» 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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