Derive equation for heat flow rate in rectangular block of solid.

Explanation

Equation for the rate of flow of heat in rectangular block is given by `(dQ)/(dt)=-kA(dT)/(dx)`, where `dQ//dt` is heat current, k is thermal conductivity, A is area of cross section and `dT//dx` is temperature gradient.
If `A=1m^(2),(dT)/(dx)=-1^(K//m)` Then `(dQ)/(dt)=k`
Thermal conductivity : ..The amount of heat flowing per second perpendicularly between two adjacent parts of a solid having unit area os cross section and unit temperature gradient is called thermal conductivity of the material of solid...
Unit of `("Joule/sec")/(m^(2)xx("Kelvin")/(m))="Joule s"^(-1)K^(-1)m^(-1)`
`("cal/sec")/("cm"^(2)xx(""^(@)C)/(cm))="cal s"^(-1)"cm"^(-1)""^(@)C^(-1)`