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What is the frequency of orange light?

What is the frequency of orange light?

Light is a form of electromagnetic radiation that can be seen by the human eye. The frequency of light determines its color. Orange light has wavelengths between 585-620 nanometers, which corresponds to frequencies between 484-517 terahertz.

The Electromagnetic Spectrum

The electromagnetic spectrum encompasses all types of electromagnetic radiation, including radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, and gamma rays. These types of radiation differ in their wavelength and frequency.

Wavelength refers to the distance between consecutive peaks or troughs in an electromagnetic wave. It is commonly measured in meters, centimeters, or nanometers (1 x 10-9 meters). Wavelength decreases as frequency increases, and vice versa. Frequency refers to the number of waves passing a fixed point every second and is measured in hertz (Hz).

The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. It ranges in wavelength from approximately 380-750 nanometers. The visible colors from longest to shortest wavelength are: red, orange, yellow, green, blue, indigo, and violet.

Properties of Orange Light

Orange light has wavelengths between 585-620 nm. This range falls between red light (620-750 nm) and yellow light (570-590 nm) within the visible spectrum. The frequencies corresponding to these wavelengths are:

Color Wavelength Range (nm) Frequency Range (THz)
Red 620-750 400-484
Orange 585-620 484-517
Yellow 570-590 508-526

So orange light has frequencies between 484-517 terahertz (THz). This range falls between red and yellow light on the electromagnetic spectrum.

Relationship Between Wavelength and Frequency

Wavelength and frequency are inversely related. As wavelength increases, frequency decreases. As wavelength decreases, frequency increases. This relationship is described by the equation:

c = λf

Where c is the speed of light in a vacuum (299,792,458 m/s), λ is the wavelength, and f is the frequency.

Rearranging this equation to solve for frequency gives:

f = c/λ

So for orange light with a wavelength of 600 nm, the frequency would be:

f = (299,792,458 m/s) / (600 x 10-9 m) = 499 THz

This demonstrates how the shorter wavelengths of orange light correspond to higher frequencies compared to the longer wavelengths of red light.

Perception of Orange Light

Orange light stimulates the cones in the human eye that are most sensitive to wavelengths around 564 nm. When these medium/long wavelength sensitive cones are stimulated, the brain interprets the color as orange.

The perception and definition of color is subjective. The boundaries between spectral colors like red, orange, and yellow are not definitive. Orange is commonly defined as having wavelengths between 585-620 nm, but the exact perception of orange can vary slightly among different people.

Factors like the intensity and surrounding colors can influence the perceived orange color. But in general, light within the wavelength range of 585-620 nm will be observed as orange due to the stimulation of the medium/long cones in the retina.

Sources of Orange Light

There are both natural and artificial sources of orange light:

  • Sunset – As the sun sets, its light passes through more atmosphere which scatters away the shorter visible wavelengths, leaving the longer orange/red wavelengths to reach the eye.
  • Candle flame – Emission spectra from heated carbon particles emit a band of orange light.
  • Sodium vapor lamps – These gas-discharge lamps emit narrowband orange light from excited sodium atoms.
  • Orange LEDs – Orange LEDs are constructed with Gallium Arsenide Phosphide (GaAsP) or Aluminum Gallium Indium Phosphide (AlGaInP) to emit light concentrated around 600 nm.
  • Lasers – Orange helium-neon lasers and dye lasers can be produced using certain fluorescent dyes as the gain medium.

By controlling the emission spectra, narrow ranges of orange wavelengths can be isolated from natural and artificial light sources.

Applications of Orange Light

Some uses and applications of orange light include:

  • Vision – Orange wavelengths are less scattered than shorter blue/violet wavelengths in optics applications.
  • Astronomy – Sodium D-line filters transmit orange wavelengths to detect features and enhance contrast.
  • Biology – Orange/red light is used in phototherapy for treatment of jaundice and other conditions.
  • Underwater – Since water absorbs long wavelength red light, orange light penetrates deeper underwater.
  • Safety – Orange lighting is useful for visibility and safety equipment like traffic cones.
  • Displays – Orange emitted by LEDs or phosphors is used in electronic device displays and TVs.

The specific properties of orange light lend themselves useful for these and many other optical applications across science and technology.


In summary, orange light has wavelengths of 585-620 nm which correspond to frequencies of 484-517 terahertz. This range falls between red and yellow in the visible spectrum. Due to the relationship between wavelength and frequency, shorter wavelength orange light has higher frequencies than longer wavelength red light. Orange is perceived when the medium/long cones in the retina are stimulated. Both natural and artificial light sources can emit orange wavelengths by controlling the emission spectra. Characteristics like penetration through water and visibility make orange light advantageous for many applications across diverse fields.