In this photo you can see part of the bowl, which I turned upside down and placed on top of various electromagnetic sources to determine whether the waves could pass through it. The graph in the background illustrates my results.
For the shorter wavelengths, I had to guess. I knew that ultraviolet would be blocked, but I assumed that x-rays and gamma rays could go through the bowl.
To me, is seems that wavelengths in the range of, say, 100nm to 900nm are more easily stopped by the bowl. Even though I used a metal bowl, I think a plastic or paper bowl would produce similar results.
So my question is: why are the waves in the middle of the spectrum stopped by the bowl and not those at the ends?
Here are some of the items I used in my experiment: a TV Remote, a Bluetooth device, an IPhone, our Home WiFi, a Cellular LTE, a Sprinkler Remote, and a Radio.
All of the items on my list were able to pass through the bowl except the TV remote, which I assume was infrared.