Rankers Physics
Topic: Current Electricity
Subtopic: Variation of Resistance with Temperature

Two wires of resistances R1 and R2 have temperature coefficient of resistances α1 and α2 respectively. These are joined in series. The effective temperature coefficient of resistance is :
\[\frac{\alpha_{1}+\alpha_{2}}{2}\]
\[\sqrt{\alpha_{1}\alpha_{2}}\]
\[\frac{\alpha_{1}R_{1}+\alpha_{2}R_{2}}{R_{1}+R_{2}}\]
\[\frac{\sqrt{R_{1}R_{2}\alpha_{1}\alpha_{2}}}{\sqrt{R_{1}^{2}R_{2}^{2}}}\]

Solution:

When two resistors with resistances R1R_1 and R2R_2

and temperature coefficients of resistance α1\alpha_1 and α2\alpha_2 are connected in series, the effective temperature coefficient of resistance αeff\alpha_{\text{eff}}

is given by the formula:

 

αeff=α1R1+α2R2R1+R2\alpha_{\text{eff}} = \frac{\alpha_1 R_1 + \alpha_2 R_2}{R_1 + R_2}

 

This formula takes into account the individual resistances and temperature coefficients of the two wires, considering that their total resistance is the sum of the individual resistances.

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