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Two resistances ${R_1}$ and ${R_2}$ are made of different materials. The temperature coefficient of the material of ${R_1}$ is $\alpha $ and of the material of ${R_2}$ is $ - \beta $. The resistance of the series combination of ${R_1}$ and ${R_2}$ will not change with temperature, if ${R_1}/{R_2}$ equals
  • A$\frac{\alpha }{\beta }$
  • B$\frac{{\alpha + \beta }}{{\alpha - \beta }}$
  • C$\frac{{{\alpha ^2} + {\beta ^2}}}{{\alpha \beta }}$
  • D$\frac{\beta }{\alpha }$
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