Answer:
α = 1.114 × 10⁻³ (°C)⁻¹
Explanation:
Given that:
Length of rod (L) = 1.5 m,
Diameter (d) = 0.55 cm,
Area (A) = 
Radius (r) = d / 2 = 0.275 cm,
Voltage across the rod (V) = 15.0 V.
At initial temperature (T₀) = 20°C, the current (I₀) = 18.8 A while at a temperature (T) = 92⁰C, the current (I) = 17.4 A
a) The resistance of the rod (R) is given as:

Therefore the resistivity and for the material of the rod at 20 °C (ρ) is:
b) The temperature coefficient of resistivity at 20°C for the material of the rod (α) can be gotten from the equation:
![R_T=R_0[1-\alpha (T-T_0)]\\but,R_T=\frac{V}{I}=\frac{15}{17.4}=0.862\\](https://tex.z-dn.net/?f=R_T%3DR_0%5B1-%5Calpha%20%28T-T_0%29%5D%5C%5Cbut%2CR_T%3D%5Cfrac%7BV%7D%7BI%7D%3D%5Cfrac%7B15%7D%7B17.4%7D%3D0.862%5C%5C)
Rearranging to make α the subject of formula:
