How Does Visible Light Relate to Color and Everyday Physics?
The Spectrum of Visible Light
The section of the electromagnetic spectrum visible to the human eye is called the visible spectrum. The electromagnetic radiation of the visible spectrum is called visible light or just light.
Human eyes are sensitive to the wavelength of range from 380 to 740 nanometers. This wavelength range corresponds to a band of frequency between 405-790 THz.
The visible spectrum does not contain all the colors which can be visually distinguished by the human eye.
For example, unsaturated colors like pink and purple variations like magenta are absent in the visible spectrum, because these colors can only be made by a mixture of multiple wavelengths.
The colors which are made up of only one wavelength are called pure colors or spectral colors.
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(White light dispersed by a prism to its constituent colors of the visible spectrum.)
The Electromagnetic Spectrum Visible Light
Electromagnetic waves can travel through space or vacuum. Mechanical waves require a material medium in order to transport energy, whereas electromagnetic waves can transport energy through the vacuum of outer space.
Electromagnetic waves are produced by vibrating electric and magnetic charges, and hence they are composed of both electric and magnetic components.
Electromagnetic waves exist over a wide range of wavelengths, and frequencies with a continuous range of frequencies called the electromagnetic spectrum. This entire range of the spectrum is broken down into small specific parts.
The subdivision of the electromagnetic spectrum into smaller spectra is done based on how the electromagnetic waves of each region interact with matter.
What is the Visible Spectrum of Light?
Electromagnetic waves exist in a wide range of wavelengths and frequencies, but our eyes are sensitive only to the narrow band of wavelengths & frequencies. This narrow band of wavelengths is the visible spectrum or the visible light spectrum.
Light is an electromagnetic wave, by which we are able to see.
Visible light or visible spectrum is a small part of the electromagnetic spectrum. The visible light consists of a spectrum of wavelength ranging from 400 nanometers to 700 nanometers.
More familiarly, the range of wavelength is expressed as 7 × 10-7 meters to 4 × 10-7 meters. The narrow band of visible light is also called VIBGYOR.
Wavelength and Color Spectrum Chart
The wavelength of electromagnetic radiation is related to the frequency and energy, and it determines the color of the radiation. The wavelength range of different colors is mentioned in the list below.
The boundaries of these wavelengths in the electromagnetic spectrum are not separated drastically, but they blend with each other. One edge of the visible light spectrum has the ultraviolet region, while the other edge has infrared radiations.
The visible portion of the electromagnetic spectrum is
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Each wavelength of the spectrum of visible light represents a particular color. This is why, when the light of that particular wavelength strikes the retina of our eye, we see that particular color.
Sir Isaac Newton showed that when white light is passed through a prism, it gets separated in its constituent colors of different wavelengths. This proves that the visible light is composed of various colors.
The separation of visible light into its constituent colors of different wavelengths is known as dispersion.
Every color has the characteristic of a distinct wavelength and light of different wavelength bends with different angles when it passes through a prism. For these reasons, the individual colors of visible light are dispersed when it is passed through a prism.
Dispersion of White Light through a Prism Produces the Following Colors
Violet (V)
Indigo (I)
Blue (B)
Green (G)
Yellow (Y)
Orange (O), and
Red R.
For this reason; visible light is also called VIBGYOR.
The red color of light has the longest wavelength among the visible spectrum, while the violet color of light has the shortest wavelength. Within red & violet, there is a continuous range of wavelengths.
Below is the diagram of the visible light spectrum, showing the constituent colors of the spectrum.
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Which color of the visible light spectrum has the highest frequency
The diagram below shows the regions of the electromagnetic spectrum. The longer the wavelength, the lower is the frequency, as wavelength and frequency are inversely proportional to each other.
The long-wavelength regions are located on the left side of the spectrum, whereas the shorter wavelength regions are located on the right side of the spectrum.
The visible light area & X-ray region are two narrow regions of the spectrum.
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FAQs on Visible Light in the Electromagnetic Spectrum: Wavelength & Color Explained
1. What is the visible light spectrum?
The visible light spectrum is the very small portion of the electromagnetic spectrum that the human eye can perceive. When white light, such as sunlight, passes through a prism, it separates into its constituent colours. This band of colours, arranged by wavelength, is what we call the visible light spectrum. It represents the range of electromagnetic waves to which our eyes are sensitive.
2. What are the different colours in the visible light spectrum and their approximate wavelengths?
The visible light spectrum consists of seven colours, often remembered by the acronym VIBGYOR. They are arranged in order from the shortest to the longest wavelength:
- Violet: 380–450 nm
- Indigo: 450–475 nm
- Blue: 475–495 nm
- Green: 495–570 nm
- Yellow: 570–590 nm
- Orange: 590–620 nm
- Red: 620–750 nm
Red light has the longest wavelength and lowest frequency, while violet light has the shortest wavelength and highest frequency within the visible range.
3. How does visible light fit into the broader electromagnetic spectrum?
Visible light is a tiny segment nestled between ultraviolet (UV) and infrared (IR) radiation in the full electromagnetic spectrum. The complete spectrum, ordered by increasing wavelength, includes:
- Gamma Rays
- X-rays
- Ultraviolet (UV) Rays
- Visible Light
- Infrared (IR) Radiation
- Microwaves
- Radio Waves
Visible light constitutes only about 0.0035% of the entire electromagnetic spectrum, highlighting how limited our natural vision is.
4. What are the key properties of visible light?
Visible light, as an electromagnetic wave, exhibits several key properties that are fundamental to optics and physics. The primary properties include:
- Propagation: It travels in straight lines, a property known as rectilinear propagation.
- Speed: It travels at a constant speed of approximately 3 x 108 m/s in a vacuum, often denoted as 'c'.
- Reflection: It bounces off surfaces, which is how we see non-luminous objects.
- Refraction: It bends when passing from one medium to another, like light entering water from air.
- Dispersion: It splits into its constituent colours when passing through a prism.
- Interference and Diffraction: It shows wave-like behaviours by creating patterns when passing through small openings or around obstacles.
5. Why can the human eye only detect the 'visible' portion of the electromagnetic spectrum?
The human eye's ability to see is an evolutionary adaptation. Our eyes contain photoreceptor cells called rods and cones that are sensitive to a specific range of energy levels, corresponding to the wavelengths of 380 to 750 nanometers. This range happens to be the most intense part of the Sun's radiation that reaches Earth's surface. Wavelengths shorter than violet (like UV) have too much energy and can damage eye cells, while wavelengths longer than red (like infrared) do not have enough energy to trigger a chemical reaction in our photoreceptors. Therefore, our vision is biologically tuned to this specific, safe, and abundant 'window' in the electromagnetic spectrum.
6. How are the colour, wavelength, and frequency of visible light related?
The colour of visible light is determined by its wavelength or, alternatively, its frequency. These three properties are intrinsically linked. Wavelength and frequency are inversely proportional; as one increases, the other decreases. This relationship is described by the equation c = fλ, where 'c' is the speed of light, 'f' is the frequency, and 'λ' (lambda) is the wavelength. For example, red light has a long wavelength and a low frequency, while violet light has a short wavelength and a high frequency. Each distinct colour we perceive corresponds to a unique wavelength and frequency.
7. Why does white light split into a spectrum of colours when it passes through a prism?
This phenomenon, known as dispersion, occurs because the refractive index of the prism's material (like glass) is slightly different for each wavelength of light. According to the principles of refraction, when light enters a new medium at an angle, it bends. The amount of bending depends on the light's wavelength. Violet light (shorter wavelength) bends the most, while red light (longer wavelength) bends the least. Since white light is a mixture of all visible colours, each colour bends at a slightly different angle upon entering and exiting the prism, causing them to separate and form a visible spectrum.
8. What are some important real-world applications of visible light beyond just seeing?
Besides enabling vision, visible light is crucial for many modern technologies. Some important applications include:
- Optical Fibres: Used in telecommunications to transmit data over long distances with minimal signal loss.
- Lasers: Employed in various fields, from barcode scanners and Blu-ray players to medical surgery (photomedicine) and industrial cutting.
- Photography and Videography: Capturing and storing images by focusing light onto digital sensors or film.
- Photosynthesis: The fundamental process by which plants use sunlight to convert carbon dioxide and water into food, sustaining most life on Earth.
- Li-Fi (Light Fidelity): An emerging wireless communication technology that uses visible light to transmit data at high speeds.
