Testing some LaTeX

Just testing some $\LaTeX$. Some of the world’s most favourite equations:

$\nabla \cdot \textbf{D} = \rho \\ \nabla \cdot \textbf{B} = 0 \\ \nabla \times \textbf{E} = \frac{\partial \textbf{B}}{\partial t} \\ \nabla \times \textbf{H} = \frac{\partial \mathbf{D}}{\partial t} + \mathbf{J}$

$\mathbf{F} = m\mathbf{a}$

$a^2 + b^2 = c^2$

$H\psi = E\psi$

$E = mc^2$

$S = k \ln W$

$1+1 =2$

$\delta S = 0$

$p = \frac{h}{\lambda}$