question_answer

STATEMENT - 1 The temperature dependence of resistance is usually given as\[R={{R}_{0}}(1+\alpha \,\,\Delta t)\]. The resistance of a wire changes from\[100\,\Omega \]to \[150\,\Omega \] when its temperature is increased from\[27{}^\text{o}C\]to\[227{}^\text{o}C.\] This implies that\[\alpha =2.5\]\[\times {{10}^{3}}/{}^\text{o}C.\] STATEMENT - 2 \[R={{R}_{0}}(1+\alpha \text{ }\Delta t)\]is valid only when the change in the temperature DT is small and\[\Delta R=(R{{R}_{0}})<<{{R}_{0}}.\]     AIEEE  Solved  Paper-2009

A) Statement - 1 is True, Statement - 2 is False.

B) Statement - 1 is True, Statement - 2 is True; Statement - 2 is a correct explanation for Statement - 1.

C) Statement - 1 is True, Statement - 2 is True; Statement - 2 is not the correct explanation for Statement - 1.

D) Statement - 1 is False, Statement - 2 is True.

Correct Answer: D

Solution :

\[{{R}_{0}}\]is the resistance at\[0{}^\text{o}C.\] Directions: Question numbers 12 and 13 are based on the following paragraph. A current loop ABCD is held fixed on the plane of the paper as shown in the figure. The arcs BC (radius = b) and DA (radius = a) of the loop are joined by two straight wires AB and CD. A steady current I is flowing in the loop. Angle made by AB and CD at the origin O is\[30{}^\text{o}.\] Another straight thin wire with steady current\[{{I}_{1}}\]flowing out of the plane of the paper is kept at the origin.