Visible Spectrum
Definition and meaning of Visible Spectrum in chemistry.
The visible spectrum is the range of electromagnetic radiation with wavelengths between approximately 380 and 750 nanometers that human eyes can directly detect. It represents the only portion of the electromagnetic spectrum perceptible to unaided human vision.
In more detail
Within this wavelength range, different colors correspond to specific intervals: violet (380-450 nm), blue (450-495 nm), green (495-570 nm), yellow (570-590 nm), orange (590-620 nm), and red (620-750 nm). The mnemonic ROYGBIV describes the color sequence, though indigo is often considered a transition between blue and violet rather than a distinct color. The visible spectrum occupies only a minuscule slice of the full electromagnetic spectrum, which extends from radio waves with wavelengths of kilometers down to gamma rays with wavelengths of picometers or smaller; because the electromagnetic spectrum has no fixed upper or lower bound, the visible fraction is far less than 1 percent rather than a precisely defined percentage. The color of most objects is determined by which visible-spectrum wavelengths they absorb, transmit, or reflect.
Key facts
| Wavelength Range | 380-750 nanometers (nm) |
|---|---|
| Color Order | Red (longest) to violet (shortest) wavelength |
| Fraction of EM Spectrum | A minuscule slice (far less than 1 percent) |
| Field | Physical Chemistry |
When white sunlight passes through a prism, it refracts and separates into distinct colored bands spanning the visible spectrum, from red light (longest wavelength) to violet light (shortest wavelength). This same phenomenon occurs naturally in rainbows.
Frequently asked questions
Why cannot humans see ultraviolet or infrared radiation?
Human eyes contain photoreceptor cells (cones and rods) sensitive only to wavelengths between about 380 and 750 nm. Ultraviolet light is shorter and infrared is longer than this range, so light outside the visible spectrum cannot stimulate these receptors.
Does the visible spectrum vary between individuals?
Most humans share approximately the same visible range, though some variation exists due to age, eye pigmentation, and lens clarity. A small number of people with tetrachromacy may perceive subtle color distinctions beyond typical visible-spectrum colors.