We mostly observe using our eyes. Give an example of an observation that cannot be made with the eyes. plz help me someone

Ultraviolet light causes substances to fluoresce and give off visible light.

Explanation:

Ultraviolet light is a part of the electromagnetic spectrum that includes electromagnetic waves which have wavelength just shorter than the visible light, so they are not directly visible to human eye.

Fluorescence occurs when ultraviolet light hits the atoms of some substances: the electrons in the shells of the atoms gain energy (absorbed from the ultraviolet radiation) and jumps to higher energy levels, then they de-excite re-leasing part of the energy back, but in a different wavelength region, corresponding to visible light. Therefore, these substances absorb radiation in the ultraviolet region and re-emit radiation in the visible light region.