Question

What type of electromagnetic energy is invisible to the human eye?

Answer 1

Any electromagnetic energy that is smaller than 400 nanometres or larger than 700 nanometres.

Explanation:

The electromagnetic spectrum is vast, ranging from the smallest Gamma waves at `10^-6` nanometres, to the largest radio waves at 100 km. Out of this whole spectrum, our eyes have only evolved to see a tiny, 300-nanometer range of it all. This range is between 400-700 nanometers and includes every single color we can see with our naked eye.

Just above our view is the infra-red section, and just under is ultra-violet. Why our eyes only evolved to see such a small part of the spectrum, I don't know. But thanks to this, Any electromagnetic energy that is smaller than 400 nanometers or larger than 700 nanometers is invisible to the human eye.

I hope that helped!