diff --git a/content/physics/thermodynamics.md b/content/physics/thermodynamics.md index 43dd016..66e5bed 100644 --- a/content/physics/thermodynamics.md +++ b/content/physics/thermodynamics.md @@ -25,7 +25,7 @@ When it comes to energy transfer and phase changes there are only two useful equ These equations together describe the heat energy required for changing the temperature of a substance and for changing its phase. -**It is important to note the alternate arrangement of both: +**It is important to note the alternate arrangement of both**: $$ Q=nc_{\mathrm{mol}}\Delta T = \Delta \textbf{KE} $$ @@ -91,3 +91,16 @@ P_b=A\varepsilon \sigma\cdot T^4 $$ Where $A$ is the area of the exposed surface. +## Emissivity and Albedo + +Emissivity $\varepsilon$ is given by : +$$ +\varepsilon=\frac{P_{\text{obj}}}{P_b} +$$ +Albedo is given by: +$$ +\alpha=\frac{P_\text{reflected}{P_{\text{incoming}}}} + +This is where the Boltzmann law comes in to play. In order to calculate the emissivity of an object, you first need bot: the power of emissions from the target object, and the Power that would be emitted by a black body of the same temperature. This value can be procured using the Stefan Boltzmann Law of Radiation. + +Albedo, however, is a far simpler quantity, relying only on the input and output energies of the object.