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Two wires of resistance `R_(1)` and `R_(2)` have temperature coefficient of resistance `alpha_(1)` and `alpha_(2)` respectively. These are joined in series. The effective temperature coefficient of resistance isA. `(alpha_(1)+alpha_(2))/(2)`B. `sqrt(alpha_(1)alpha_(2))`C. `(alpha_(1)R_(1)+alpha_(2)R_(2))/( R_(1)+R_(2))`D. `(sqrt(R_(1)R_(2)alpha_(1)alpha_(2)))/(sqrt(R_(1)^(2)+R_(2)^( 2)))` |
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Answer» Correct Answer - 3 `R_(1)=R_(1)(1+prop_(1) theta),R_(2)=R_(2)(1+prop_(2)theta)` `R_("net")=R_(1)+R_(2)=R_(1)(1+prop_(1)theta)+R_(2)(1+prop_(2)theta)` `=R_(1)+R_(2)+theta(R_(1)prop_(1)+R_(2)prop_(2))` `=( R_(1)+R_(2))[1+(R_(1)prop_(1)+R_(2)prop_(2))/(R_(1)+R_(2))theta]` compair this equation `R=R_(0)(1+prop_("net")theta)` `therefore prop_("net")=(R_(1)prop_(1)+R_(2)prop_(2))/(R_(1)+R_(2))` |
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