Current Electricity · JEE Main previous year questions

2010 3 questions

1. Q432010 · 25 Apr 2010 · Shift 1

   Two conductors have the same resistance at $0^{\circ }\mathrm{C}$ but their temperature coefficients of resistance are ${\alpha }_1$ and ${\alpha }_2$. The respective temperature coefficients of their series and parallel combinations are nearly

   1. A.$\frac{{\alpha }_1+{\alpha }_2}{2}$, ${\alpha }_1+{\alpha }_2$
   2. B.${\alpha }_1+{\alpha }_2$, $\frac{{\alpha }_1+{\alpha }_2}{2}$
   3. C.${\alpha }_1+{\alpha }_2$, $\frac{{\alpha }_1{\alpha }_2}{{\alpha }_1+{\alpha }_2}$
   4. D.$\frac{{\alpha }_1+{\alpha }_2}{2}$, $\frac{{\alpha }_1+{\alpha }_2}{2}$
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   Answer: D

2. Q492010 · 25 Apr 2010 · Shift 1
   
   1. A.$I_1=-I_2=\frac{Blv}{6R}$, $I=\frac{2Blv}{6R}$
   2. B.$I_1=I_2=\frac{Blv}{3R}$, $I=\frac{2Blv}{3R}$
   3. C.$I_1=I_2=I=\frac{Blv}{R}$
   4. D.$I_1=I_2=\frac{Blv}{6R}$, $I=\frac{Blv}{3R}$
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   Answer: B

3. Q502010 · 25 Apr 2010 · Shift 1
   
   1. A.$\frac{V{R}_1{R}_2}{\sqrt{R_1^2+R_2^2}}$ at $t=0$ and $\frac{V}{R_2}$ at $t=\infty$
   2. B.$\frac{V}{R_2}$ at $t=0$ and $\frac{V(R_1+R_2)}{R_1{R}_2}$ at $t=\infty$
   3. C.$\frac{V}{R_2}$ at $t=0$ and $\frac{V{R}_1{R}_2}{\sqrt{R_1^2+R_2^2}}$ at $t=\infty$
   4. D.$\frac{V(R_1+R_2)}{R_1{R}_2}$ at $t=0$ and $\frac{V}{R_2}$ at $t=\infty$
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   Answer: B