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(B) Supply voltage,$V = 230 \; V$.Initial current,$I_1 = 3.2 \; A$.Initial resistance $R_1 = \frac{V}{I_1} = \frac{230}{3.2} = 71.875 \; \Omega$.Stead

Vedclass · Accepted Answer

$867.5$

Vedclass · Answer

(B) Supply voltage,$V = 230 \; V$.Initial current,$I_1 = 3.2 \; A$.Initial resistance $R_1 = \frac{V}{I_1} = \frac{230}{3.2} = 71.875 \; \Omega$.Steady state current,$I_2 = 2.8 \; A$.Steady state resistance $R_2 = \frac{V}{I_2} = \frac{230}{2.8} \approx 82.143 \; \Omega$.Temperature coefficient of resistance,$\alpha = 1.70 	imes 10^{-4} \; ^{\circ}C^{-1}$.Initial temperature,$T_1 = 27.0^{\circ} C$.Using the formula $R_2 = R_1[1 + \alpha(T_2 - T_1)]$,we get:$T_2 - T_1 = \frac{R_2 - R_1}{\alpha R_1}$.$T_2 - 27 = \frac{82.143 - 71.875}{1.70 	imes 10^{-4} 	imes 71.875}$.$T_2 - 27 = \frac{10.268}{0.01221875} \approx 840.35$.$T_2 = 840.35 + 27 = 867.35^{\circ} C \approx 867.5^{\circ} C$ (rounding to match options).

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