Question

b) A copper wire has a resistance of 5000 at 20°C and resistance of 580 Q at 60 °C. Determine
the temperature coefficient of resistance.​

Answer 1

Answer:

-0.19

Explanation:

Using

$\\\tt R_{2}= R_{1} [1+\alpha (T_{2} - T_{1}) ]$

Let  T1 = 20 C and T2 = 60 C and respective

resistances  R1= 580 $\Omega$ , R2 = 5000 $\Omega$

Substitute and solve,

$\\\tt 5000 = 580 [1 + \alpha (60^{\circ} - 20^{\circ})]\\\\\tt \alpha = \dfrac{\dfrac{5000-580}{580}}{-40^{\circ}} = -0.19$

PS. The answer here feels weird since never saw with -ve temperature coefficient of resistance  of Copper but it is what it is.