#poynting vector

Introduction to Intensity In physics, intensity is a measure of the energy flux, or the power per unit area. It is commonly used to describe various phenomena such as light, sound, and electric fields. It quantifies how much energy passes through a specific area in a given time period. Mathematical Definition of Intensity In the most general sense, the intensity ($I$) is defined as the power…

Total internal reflection and Brewster’s angles

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Total internal reflection

From Snell’s second law we have

\begin{equation}\label{eqn:brewsters:20} \theta_t = \arcsin\lr{ \frac{n_i}{n_t} \sin\theta_i }. \end{equation}

This is plotted in fig. 3.

fig. 3. Transmission angle vs incident angle.

  For the \( n_i > n_t \) case, for example, like shining from glass into air, there is a critical…