Two resistances equal at $0\,^oC$ with temperature coefficient of resistance $\alpha _1$ and $\alpha _2$ joined in series act as a single resistance in a circuit. The temperature coefficient of their single resistance will be
  • A${\alpha _1}\, + \,{\alpha _2}$
  • B$\frac{{{\alpha _1}{\alpha _2}}}{{{\alpha _1}\, + \,{\alpha _2}}}$
  • C$\frac{{{\alpha _1}\, - \,\,{\alpha _2}}}{2}$
  • D$\frac{{{\alpha _1}\, + \,\,{\alpha _2}}}{2}$
AIIMS 2011, Medium
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