The SI unit of Thermal Conductivity is

Concept:

• 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:

Or, \(Q = \frac{{KA\left( {{T_1} - {T_2}} \right)t}}{x}\)

where K = Coefficient of thermal conductivity of the material.

Rate of conduction of heat energy is given by:

\(\frac{{dQ}}{t} = \frac{{KA\left( {{T_1} - {T_2}} \right)}}{x} = KA\frac{{{\bf{\Delta }}T}}{x}\)

Calculation:

Given:

Rate of conduction of heat energy is given by:

\(\frac{{dQ}}{t} = \frac{{KA\left( {{T_1} - {T_2}} \right)}}{x} = KA\frac{{{\bf{\Delta }}T}}{x}\)

Coefficient of thermal conductivity of material will be,

\(K = \frac{{dQ \times x}}{{t \times A \times {\rm{\Delta }}T}}\)

SI unit of Q = J/s = W, A = m2, x = m and ΔT = K

\(\therefore K = \frac{{dQ \times x}}{{t \times A \times {\rm{\Delta }}T}} = \frac{{J \cdot m}}{{sec \cdot {m^2} \cdot K}} = W{m^{ - 1}}{K^{ - 1}}\)

Therefore, the SI unit of the thermal conductivity is Wm-1K-1.