In Infared you see heat etc. But what would you see in UV?

Answer 1

There's confusion about heat and infra-red.

Any electromagnetic radiation emits photons, and *any* photons can heat a target - it's just that, by the time you get to the short wavelengths around infra-red, photons are energetic enough to cause significant heating.

The photons in your microwave oven are doing a pretty good job of heating, too!

So, the question can be answered one way - any wavelengths of normal intensities (leaving aside the microwave!) around infra-red and shorter have heating effects - think of how the sun's UV can cause sunburn.

So the best answer comes from this question: what materials respond to any particular wavelength?

For visible light, a white/shiny object responds well, and we can see it. For U-V, a fluorescent object (such as some gemstones and minerals) responds by re-emitting visible light, which we then see.

Without the fluorescent effect, you'd need an instrument a bit like night-vision goggles, but one that picks up U-V and displays it as visible light, and such "image converters" do exist.

The alternative is to use a U-V sensitive TV/digital camera, or U-V sensitive photographic film.

Many insects can see into the near U-V range, and some flowers reflect U-V in patterns that are attractive to those insects.