quick fix on the closing of $

content/physics/thermodynamics.md

@@ -81,7 +81,7 @@ In the above equation,:
 
 - $E_b$ is the **Emissive Power** of a black body, per unit time, per unit area.
 - $\varepsilon$ is the emissivity of an object 
-- $\sigma$ is the Boltzmann constant, about $\approx 5.670374419\cdot 10^{-8} \mathrm{W}\cdot\mathrm{m}^{-2}\cdot \mathrm{K}^{-4}
+- $\sigma$ is the Boltzmann constant, about $\approx 5.670374419\cdot 10^{-8} \mathrm{W}\cdot\mathrm{m}^{-2}\cdot \mathrm{K}^{-4}$
 - A perfect black body has an emissivity of $1$, and an albedo of $0$
 - always work in default SI units