# Which light has a high wavelength?

## wavelength

The wavelength is the distance between two successive phase points of a periodic wave. It is indicated with the symbol λ (Greek letter lambda). In addition to the wavelength, the amplitude (deflection) also plays an important role in describing the wave.

A wavelength corresponds to a period (the smallest unit of a regularly repeating physical phenomenon), mathematically also referred to as an interval. The term "wavelength", the one spatial Component, corresponds to the "Period duration"that the temporal Component describes. The formula is:

With the help of Sense organs A person can perceive certain wavelengths (frequencies) with their ears and eyes.

### Sound waves (ear)

The ear can perceive sound waves in the wavelength range from 17 mm (millimeters) to 21 m (meters), which corresponds to a sound spectrum of around 20 Hertz to 20 KiloHertz (20,000 Hz) - with a sound propagation speed in the air of around 343 meters per second. With increasing age, however, the ability to perceive higher frequencies decreases (high tones, e.g. beeps).

### Light, color (eye)

Light is that part of electromagnetic radiation that we can see with our eyes. The light spectrum, i.e. the wavelengths of visible light, is between 380 nanometers and 780 nm. The shorter the wavelength, the higher the frequency, and the more energy a light quantum contains (so-called photon energy). Blue light has more photon energy than red.

Electromagnetic radiation spreads in a vacuum at the speed of light (around 300,000 km per second). The relationship between their frequency and the assigned wavelength results from the formula:

Descriptions of the rainbow have been known since ancient times. But the first to use a prism to break up white sunlight and thus make the light spectrum visible was Isaac Newton - at least the first to document it scientifically.

### Colours

The wavelengths of the main colors are:

 violet approx. 380 to 430 nm blue approx. 430 (ultramarine blue) to 490 nm (Prussian blue) green approx. 490 to 570 nm yellow approx. 570 (green-yellow) to 600 nm (orange-yellow) orange approx. 600 nm to 640 nm red approx. 640 nm (orange-red) to 780 nm (madder-red)

### Sight (eye)

The fact that we can see light at all has to do with our eyes. These are sensory cells that have developed in the course of evolution in such a way that they can convert physical forces from our environment in such a way that we can process them in the brain. The human eye has four different sensory cells for this, each of which is "activated" at different wavelengths or at different light intensities. For more information, see "Eye: Structure and Functionality".