This question contains Statement-1 and Statement-2. Of the four choices given after the statements, choose…
This question contains Statement-1 and Statement-2. Of the four choices given after the statements, choose the one that best describes the two statements.
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 $27^{\circ} \mathrm{C}$ to $227^{\circ} \mathrm{C}$. This implies that $\alpha=2.5 \times 10^{-3} /{ }^{\circ} \mathrm{C}$.
Statement 2: $R=R_i(1+\alpha \Delta T)$ is valid only when the change in the temperature $\Delta T$ is small and $\Delta R=$ $\left(R-R_0\right) \ll R_0$.
Statement-1 is true, Statement-2 is false
Statement-1 is true, Statement-2 is true; Statement-2 is the correct explanation of Statement-1.
Statement-1 is true, Statement-2 is true; Statement-2 is not the correct explanation of Statement-1.
Statement-1 is false, Statement-2 is true
Solution
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\text { Directions: Question numbers } 12 \text { and } 13 \text { are based on the following paragraph. }
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A current loop $A B C D$ is held fixed on the plane of the paper as shown in the figure. The arcs $B C$ (radius $=b$ ) and $D A$ (radius $=a)$ of the loop are joined by two straight wires $A B$ and $C D$. A steady current $I$ is flowing in the loop. Angle made by $A B$ and $C D$ at the origin $O$ is $30^{\circ}$. Another straight thin wire with steady current $\mathrm{l}_1$ flowing out of the plane of the paper is kept at the origin.
