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    Question

    A heating element using nichrome connected to a 230 V

    supply draws an initial current of 3.2 A which settles after a few seconds to a steady value of 2.8 A. What is the steady temperature of the heating element if the room temperature is 27.0 ┬░C ?Temperature coefficient of resistance of nichrome averaged over the temperature range involved is 1.70 ├Ч 10-4┬░C-1.
    A 827┬░C Correct Answer Incorrect Answer
    B 877┬░C Correct Answer Incorrect Answer
    C 857┬░C Correct Answer Incorrect Answer
    D 867┬░C Correct Answer Incorrect Answer

    Solution

    At room temperature 27┬░C, the resistance of the heating element. R27┬░ = 230/3.2 = 71.875 ohm At the steady temperature t┬░ C, the resistance Rt = 280/2.8 = 82.143 ohm Now, R2 = R1[1 + ╬▒(t2 - t1) => 82.143 = 71.875[1 + 1.7 x 10-4(t - 27)] => 0.0840 x 104 = t - 27 => 840 = t - 27 => t = 867┬░C

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