White Light

What is White Light?

The complete blend of all the wavelengths of the visible spectrum is known as the white light. This indicates that if a person has a beam of light of all the colors of the rainbow and focuses all them onto a single spot, the combination of all colors will result in a beam of white light.


White light or visible light comes above infrared rays. At its zenith power, the Sun emits the visible light. However, combining the entire emission power spectrum passes all wavelengths showing that the Sun emits slightly more infrared than visible light.


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White light or visible light is the part of the electromagnetic spectrum which can be identified by a human eye. White light or its near-infrared light is typically absorbed and emitted by the electrons in atoms and molecules that shift from one energy level to another. The chemical mechanism that triggers human vision and plant photosynthesis is based on this phenomenon.


Electromagnetic Spectrum

Electromagnetic spectrum comprises a different type of electromagnetic waves, each with different wavelengths or frequencies. For example, gamma rays, infrared radiation, x-rays, and ultraviolet radiations are examples of electromagnetic waves. Human eye can only see a small portion of the spectrum of wavelengths. Visible spectrum is also known as the visible portion of the electromagnetic spectrum. This shows the full spectrum of electromagnetic radiation and highlights the small part of the spectrum that is the visible spectrum.


Light Spectrum Definition

The variety of wavelengths of energy produced by a light source is known as the light spectrum. The unit of measurement of light is nanometers (nm). Each wavelength of the light or band of light energy is represented by a nanometer and has a spectrum of visible light within the range of 380 mm to 780 mm.


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Here the light spectrum can mean the visible spectrum.


Visible spectrum implies the light spectrum, the range of wavelengths of electromagnetic radiation that our eyes are sensitive to, or the mean plot (or chart or graph) of the intensity of light against its wavelength (sometimes, its frequency). 


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Light refers to what we see or to a piece of the electromagnetic spectrum that operates on the optical telescope (especially on the ground) (and sometimes, irregularly, which means the entire electromagnetic spectrum or any electromagnetic radiation).


Therefore, we can say that spectrum is the splitting of white light into its constituent colors when passed via a prism. However, it can also be done on the light having more than one constituent color where the frequency need not be just a white light.


How is White Light Produced?

White light can be generated by a variety of white light sources, both in space and artificial sources on earth. For example: the stars and Sun are the sources of white light. The obvious source of white light in the solar system is the Sun. The white LED's and fluorescent light bulb producing white light  is an artificial source of light. However, the incandescent lamp, other light bulbs do not produce white light, rather it produces light of a much longer wavelength within the red to yellow range.


Wavelength of White Light

Depending on the wavelength, one can see the visible light colour. Above 700 mm and below 400 mm, the light is not visible. The white light is made up of seven colors viz: violet, green, indigo, orange, blue, yellow, and red. Here, the wavelength of red is 400 mm, and that of violet is 700 mm. Hence white cannot be assigned to a single wavelength as it is composed of wavelengths of different colors. So, the white light has the wavelength between the ranges of 400 – 700 mm.


Characteristics of White Light

The so-called white light is all around us. Most of the light coming from the sky or our interior home and office light allows us to see things. So the focus is the most important thing I can think of although it can also be said that life on the planet provides both heat and energy.

  • When white light is transmitted from the prism or diffraction grating, the colors of the visible spectrum appear. 

  • Colors vary according to their wavelength. 

  • Violet has the highest frequency and the shortest wavelengths, and red has the lowest frequency and the longest wavelengths.


Difference Between White Light and Sunlight

White Light

  • A blend or mixture of colors is known as the white light, which gives the eye sensation of white. As we know, if the green, red, and blue light is mixed in the proper portion, we get the white light. Many combinations of light give white light.

  • Every white light does not have a continuous spectrum. When we energize the hydrogen gas, it emits white light while its spectrum is distinct.

Sunlight

  • Sunlight is the combination of all wavelengths of the visible region spectrum of the Sun. Or simply put the radiations of Sun in the visible region. Also, the sunlight gives our eyes the sensation of white; hence the sunlight is known as the white light.

  • We also know that the sunlight spectrum is continuous. 

So sunlight is a subcategory of white light.

FAQ (Frequently Asked Questions)

1. Why do we see a White Light?

Ans- Whenever color is seen, it is just a small portion of wavelength. By the mixture of wavelengths, we see the formation of white color (i.e., the color of the rainbow). For example, when a person sees any blue color, the eye absorbs the entire wavelength except that of blue. When we see black, your eyes don't see anything as it reflects back. Now for white, a person's eye absorbs all the mixture of colors. It is the result of the mixture of all the wavelengths. Thus due to the wave nature of our eyes, the colour appears to be white.

2. What is the Application of White Light?

Ans- Many objects, including the Sun in the space, are  natural sources of white light. 

  • On earth, white LEDs and the white fluorescent bulbs are an artificial source of light. 

  • White light can be separated back to different colors with the help of a device like a prism.