Our eyes are detectors which are designed to detect visible light waves (or visible radiation). ... The electromagnetic spectrum includes gamma rays, X-rays, ultraviolet, visible, infrared, microwaves, and radio waves. The only difference between these different types of radiation is their wavelength or frequency.
No the density does not change. Density is a ratio D=m/v no matter how much of a substance you have its mass will be proportional. When doing density labs sometimes you might get different answers due to errors that are unavoidable.
