Physics
Frequency Spectrum
Quick fact
When sunlight passes through a prism, the rainbow you see is actually the frequency spectrum of visible light—and beyond both ends lie invisible infrared and ultraviolet frequencies.
Why this is interesting
If you press a single key on a piano, you hear a pure tone—but when you listen to a chord, how does your ear separate the notes? The answer lies in the frequency spectrum, a hidden map of every sound's ingredients.