# What experiments confirmed Poynting's Theorem?

Actually, I have two related questions. The fist is the above question. The second is, what experiments confirmed that $\varepsilon_0\left(\frac{E^2}{2} + c^2 \frac{B^2}{2}\right)$ is the electromagnetic energy density?

I have been looking all over the place, online for such answers, but search algorithms aren't the best at distinguishing between requests for historical background, and requests for theoretical explanations of a phenomenon.

Google scholar isn't much better because of paywalls.