Last updated: September 3, 2019

What Does Wavelength Mean?

Wavelength is known as the direction between two troughs in a transverse wave. Light never travels in a straight line—it always moves in the form of transverse waves. Wavelength is measured in units of micrometers or nanometers.

Visible lights mainly have the wavelengths of 400 to 700 nanometers. The wavelength, in terms of physics, is a spatial period of any periodic wave determined by measuring the distance between two consecutive points of the same phases of a wave, which include crests, troughs, or zero crossings. It is usually denoted by a lambda.

Safeopedia Explains Wavelength

We can see colors because the retina of our eyes contains two types of photoreceptors: rods and cones. Rods help detect colors like white, black, and grey, while cones help detect the other colors. The visible spectrum of light contains rays that have different wavelengths, which is broken down below:

  • Ultraviolet light: Its wavelength extends in the range of 10 to 400 nm and is named ultraviolet ray because this light is close to the violet end of the spectrum.
  • White light: Its wavelength extends in the range of 400 to 750 nm.
  • Infrared light: It has a longer wavelength in the range of 750 nm to 1 mm. It can be felt like a form of heat.
  • Yellow light: It has a wavelength in the range of 590 to 570 nm.
  • Green light: Its wavelength extends in the range of 570 to 500 nm. Grass absorbs all wavelengths and only reflects a green color.
  • Blue light: Its wavelength extends in the range of 500 to 450 nm. The atmosphere sprays wavelengths that are shorter and thus makes the atmosphere blue.
  • Indigo and violet light: Indigo’s wavelength extends in the range of 450 to 425 nm. Violet’s wavelength extends in the range of 425 to 400 nm. It has the shortest wavelength, which is sprayed in a more effective way by the atmosphere.
  • Red and orange light: These wavelengths extend in the range of 750 to 610 nm and 610 to 590 nm.

Apart from the light rays in the visible spectrum, there are certain other rays in the invisible spectrum too that cannot be viewed with the naked eyes.

Now the question arises regarding which light can affect our eyes. Many of us think that UV rays are responsible for damaging the skin or causing skin cancer, but they may cause damage to our eyes as well. It is light that is not visible, and part of the spectrum comes from the sun directly.

Excessive UV rays can cause damage to the front surface of eyes and cause diseases like cataracts (damage to the lens), pterygium (damage to the cornea or corners of the eyes), and photokeratitis (which may burn the cornea).

We can detect colors, and our perception of color is completely based on the light wavelength’s perception. The human eyes cannot feel the sensitivity of all wavelengths of visible light. Keep in mind that our eyes respond differently per wavelength at the time of light and dark conditions.


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