A wire has resistance of 60 W at temperature 27°C. When it is connected to a 220 V dc supply, a current 2.75 A flows through it at a certain temperature. Find the value of temperature, if coefficient of thermal resistance (µ) is 2 × 10^–4/°C.

<p><span lang="EN-IN">Final resistance <span contenteditable="false"> <math> <mrow> <mrow> <mo> (</mo> <mrow> <mi>R</mi> </mrow> <mo>)</mo> </mrow> <mo>=</mo> <mfrac> <mrow> <mi>V</mi> </mrow> <mrow> <mi>I</mi> </mrow> </mfrac> <mo>=</mo> <mn>8</mn> <mn>0</mn> <mtext> </mtext> <mi>Ω</mi> </mrow> </math> </span>&lt;!- [endif]-&gt;&lt;!- [if gte mso 9]>&lt;xml&gt; <o:OLEObject Type="Embed" ProgID="Equation.DSMT4" ShapeID="_x0000_i1025" DrawAspect="Content" ObjectID="_1820395741"> </o:OLEObject>&lt;/xml&gt;&lt;! [endif]-&gt;</span></p><p><span lang="EN-IN">then, R = R₀ (1 + </span><span lang="EN-IN">µ</span><span lang="EN-IN">D</span><span lang="EN-IN">T)</span></p><p><span lang="EN-IN">80 = 60 (1 + 2 × 10^–4 </span><span lang="EN-IN">D</span><span lang="EN-IN">T)</span></p><p><span lang="EN-IN">D</span><span lang="EN-IN">T = 1666.67</span></p><p><span lang="EN-IN">T – 27</span></p><p><span lang="EN-IN">T = 1693.66</span></p><p><span lang="EN-IN">= 1694°C</span></p>

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