Question

Coefficient of linear expansion of material of resistor is $\alpha$. Its temperature coefficient of resistivity and resistance are $\alpha_{\rho}$ and $\alpha_{R}$ respectively, then correct relation is

• A. $\alpha_{R}=\alpha_{\rho}-\alpha$
• B. $\alpha_{R}=\alpha_{p}+\alpha$
• C. $\alpha_{R}=\alpha_{\rho}+3 \alpha$
• D. $\alpha_{R}=\alpha_{\rho}-3 \alpha$

Answer 1

Answer: (A)

$R=\frac{\rho l}{A}$
$\frac{\Delta R}{R}=\frac{\Delta P}{P}+\frac{\Delta l}{l}-\frac{D A}{A}$
$\alpha_{R}=\alpha_{P}+\alpha_{R}-2 \alpha$
$\alpha_{R}=\alpha_{p}-\alpha$