Correct Answer - Option 3 : W/m°K
Explanation:
Thermal Conductivity:
When one end of a metal rod is heated, heat flows by conduction from the hot end to the cold end. In this process, each cross-section of the rod receives some heat from the adjacent cross-section towards the hot end.
It is found that the amount of heat Q that flows from hot to cold face during steady-state:
\(̇{Q} = \frac{{kA\left( {{T_1} - {T_2}} \right)}}{L}\)
where k = coefficient of thermal conductivity of the material.
\(k = \frac{{̇{Q}L}}{{A {\rm{\Delta }}T}}\)
SI unit of Q̇ = J/s = W, A = m2, L = m and ΔT = K
\(k = \frac{{{W}m}}{{m^2{{K}}}}=\frac{W}{mK}\)