# Why does electromagnetic energy only pass through certain hole sizes?

I have noticed in faraday cages and in microwaves that the holes in the screen manage to prevent certain frequencies from passing through them. Why it is that this happens?

I don't believe it's the frequency, but the wavelength. The shorter the wavelength the smaller the hole (or gap) needs to be to be effective at shielding.

When you get to something like an x-ray or gamma ray you need an extremely dense material to shield from them as the wavelength is so small.

At least that's the impression I have of the subject. Perhaps someone who works in the area can confirm it.

I'm pretty sure that it is wavelength, because I've heard talk about Faraday cages and other such electromagnetic barriers, and I've heard "lambda/10 for good shielding."

Thanks for the clarification.

You guys do realize that $$c=\lambda\nu$$ right?