Wavelength of Light - Definition, Calculation, FAQs

Edited By Team Careers360 | Updated on Jul 02, 2025 05:03 PM IST

What is wavelength of light ?

There is a distance between two consecutive maxima or two consecutive minima in a transverse wave what is called wavelength of light. It is the answer for the question what is wavelength or definition of wavelength of in Physics or Chemistry. Understanding the concept of what is wavelength of helps us in understanding the propagation of light through vacuum. According to famous physicist Maxwell, light is a transverse electromagnetic wave. In understanding the concept of what is wavelength we always follow rules for transverse electromagnetic waves. The wavelength meaning in tamil is “Alianilam”.
The distance between two consecutive maxima or crests or two consecutive minima or troughs is called wavelength.

Wavelength of Light - Definition, Calculation, FAQs

The wavelength of light or visible spectrum wavelength or light spectrum wavelength or the wavelength of visible light ranges up to a certain value of wavelength. Understanding the wavelength of visible or visible light wavelength range or visible spectrum wavelength is very important in optics The visible light wavelength range is approximately 380 to 780 nanometers or visible light spectrum wavelength ranges from 380 to 780 nanometers .The wavelength of red light is approximately 700 nanometer. In Angstrom unit the wavelength of red light is 7000 Angstrom. Although the wavelength of red colour can vary from 620 nanometer to 750 nanometer. Hence in Angstrom unit the wavelength of red light can vary from 6200 Angstrom to 7500 Angstrom. The wavelength of blue light can vary from 450 nanometer to 495 nanometer .In Angstrom unit the wavelength range of blue is 4500 Angstrom to 4950 Angstrom. Wavelength of violet light is around 380 nanometer. In Angstrom unit the wavelength of violet light is 3800. Wavelength of green light is around 550 nanometer. In Angstrom unit the wavelength of green light is 5500 Angstrom. The wavelength of orange is 600 nanometer. In Angstrom unit the wavelength of orange light is 6000 Angstrom. The wavelength of yellow light is 580 nanometer. In Angstrom unit the wavelength of yellow light is 5800 Angstrom. The wavelength of indigo light varies around 425 to 445 nanometer. In Angstrom unit the wavelength of indigo light varies from 4250 to 4450 Angstrom. The conversion formula between Angstrom and nanometer is:-
The electromagnetic radiation which creates sensation of vision is called visible light.

1 Angstrom = 0.1 Nanometer

This the nm definition in science.

A visible light can be split in to seven colors. These all light colors’ color of light is determined by different wavelengths, frequencies and velocities. These seven colors of visible light are violet, indigo, blue, green, yellow, orange and red. These colors are called VIBGYOR colors. In VIBGYOR wavelength order the colors are defined as : V defines violet, I defines indigo, B defines blue, G defines green, Y defines yellow, O defines orange and R defines red. These colors are called rainbow colors too. The color of light is determined by wavelength and frequency.
The colour of light depends on different frequencies of the light.

Lambda max definition: The maximum wavelength is called the lambda max.

Red is the color which electromagnetic has the longest wavelength or largest wavelength whereas violet has the lowest or shortest wavelength of light. The wavelengths of the other colored lights fall in between the wavelength of red and violet. The wavelength range for UV spectrum of light is 4× 10^-7 to 6× 10^-10 meter.

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Wavelength chart:

Color wavelengths	Range of wavelength
Radio wave	10⁴ meter to 0.1 meter
Microwave wave	0.3 to 10^-4 meter
Infrared wave	10^-3 to 7× 10^-7 meter
Visible light wave	7× 10^-7 to 4× 10^-7 meter
UV spectrum	4× 10^-7 to 6× 10^-10 meter
X – ray wave	10^-8 to 10^-12 meter
Gamma ray wave	10^-10 to 10^-14 meter

The wavelength of light is determined by the following formula:-

Wavelength = velocity of light / frequency of the light.

We usually denote wavelength of light by λ , velocity of light by v and frequency of light by f.

Hence wavelength of light can be written as:-

λ= v/f

Lambda max calculation will be v_max/f_min

For maximum wavelength frequency should be minimum and velocity should be maximum. For minimum wavelength frequency should be maximum and velocity should be minimum.

From the above formula we can say that the wavelength of light is dependent on its velocity and frequency.

Light travels slower in glass than air because the refractive index is higher in glass. This happens due to Snell’s law.

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Frequency of light spectrum:-

Frequency of light with different wavelengths are measured in Terahertz. We call Hertz in short Hz and Terahertz in short THz. Frequency is the number of waves passing a point in space during any interval of time, usually one second. We measure frequency in Hertz. One Terahertz is equals to 10¹⁴ Hertz.

Frequency of visible light in Hz or range of visible region ranges differently for different colors. Here we will be discussing about different wavelengths of light .Frequency of red light is around 426 Terahertz. Red light has minimum frequency and maximum wavelength. Frequency of blue light is 666 Terahertz. Blue light has maximum frequency and minimum wavelength. As light is an electromagnetic wave, we can say red light is also an electromagnetic wave which has longest wavelength. Blue light is an electromagnetic wave which has lowest wavelength.

Light spectrum definition

It is commonly said as radiant energy which can produce the sensation of vision.

Amplitude of light:

The light waves have different amplitudes. The intensity of the light depends on different amplitudes of light.

Amplitude of light is defined as a.

The intensity of the light depends on different amplitudes of light. Amplitude of light is defined as a.

Wavelength selectors:-

Wavelength selectors absorb the light radiation from a sample. Then the wavelength selector either selects or rejects a certain amount of radiation. Sensitivity of the instrument depends on the bandwidths and detectability depends on transmission.

There are many types of wave length selectors. We are considering filters, grating monochromators and prism monochromators only.

Filters :-

Filters selects wavelength up to narrow bandwidths of radiation. There are 4 types of filters: (i) absorption filter (ii) cut-off filters (iii) interference filters (iv) interference wedges.

white light can be split into seven colours

Grating monochromators:-

Grating monochromators produce narrow bands of radiation. There are five components in most grating monochromators.

Prism monochromators:-

Light is refracted by the prism at two interfaces. The prism monochromator creates angular dispersion.

What is monochromatic light wavelength?

The light which has only one frequency is called monochromatic light. The corresponding wavelength of that light will be monochromatic light wavelength.

Why light is reffered to as radiation?

According to Maxwell, light is an electromagnetic transverse wave. In

Quantum concept it is considered that light carries energy. Hence light is called as radiation.

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What is optics?

Optics is a branch of physics. In optics we study the nature and properties of light. The term light is commonly used to mean a wave of photons which can produce sensation of vision. However now we use the term light to mean all kinds of radiations, both visible and invisible. The subject of optics is divided into three distinct branches on the basis of definations. The three branches of light are (a) Geometrical optics

(b) Physical optics and (c) Quantum optics.

What is Geometrical optics?

In geometrical optics many fundamental principles concerning light are studied by purely geometrical means without assuming anything regarding the nature of light. It assumes rectilinear propagation of light.

What is Physical optics?

In physical optics many experimental results are obtained by considering primarily the wave nature of light.

What is Quantum optics?

In quantum optics one considers the corpuscular nature of light and for exact analysis it requires the method of quantum mechanics.

What is an electromagnetic wave?

According to Maxwell light is electromagnetic wave. A changing magnetic field produces an electric field and a changing electric field in return produces a changing magnetic field. In this way the electromagnetic wave propagates. It propagates through vacuum.

What is UV spectrum light?

The UV light ranges from 4× 10^-7 meter to 6× 10^-1⁰ meter. The source of this type of light is the sun. The ozone layer in stratosphere absorbs this harmful UV light. The UV light is extremely harmful for us. There are some chemical elements who react with ozone in ozone layer and decreases the density of ozone in ozone layer. These substances are called ozone depleting substance. Many ozone depleting elements are manmade. Like we use ozone depleting elements in aerosol cans and refrigerant. Although many countries are trying hard to ban these types of products.

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Frequently Asked Questions (FAQs)

1. What is the wavelength of light?

The wavelength of light is the distance between two consecutive crests or troughs in a light wave. It determines the color of visible light and the properties of other types of electromagnetic radiation.

2. How is wavelength related to the frequency of light?

Wavelength and frequency are inversely related. As wavelength increases, frequency decreases, and vice versa. This relationship is described by the equation c = fλ, where c is the speed of light, f is frequency, and λ is wavelength.

3. Can light have any wavelength?

Theoretically, light can have any wavelength. However, the visible spectrum for humans ranges from about 380 nm to 740 nm. Other wavelengths exist as different forms of electromagnetic radiation, such as radio waves, X-rays, and gamma rays.

4. How does the wavelength of light affect its energy?

The energy of light is inversely proportional to its wavelength. Shorter wavelengths have higher energy, while longer wavelengths have lower energy. This is described by the equation E = hc/λ, where E is energy, h is Planck's constant, c is the speed of light, and λ is wavelength.

5. What unit is typically used to measure the wavelength of light?

The wavelength of light is typically measured in nanometers (nm) for visible light. For other electromagnetic waves, units like micrometers (μm), angstroms (Å), or even meters (m) may be used depending on the scale.

6. What is the de Broglie wavelength?

The de Broglie wavelength is the wavelength associated with a particle due to its wave-like nature in quantum mechanics. It's calculated using the equation λ = h/p, where h is Planck's constant and p is the particle's momentum.

7. What is the significance of the Compton wavelength?

The Compton wavelength is a quantum mechanical property of a particle, equal to the wavelength of a photon whose energy is the same as the rest mass of the particle. It plays a role in quantum electrodynamics and sets a limit on the minimum size of a particle.

8. How does the concept of wavelength apply to matter waves?

Matter waves, proposed by de Broglie, suggest that particles can exhibit wave-like properties. The wavelength of a matter wave is given by the de Broglie equation: λ = h/p, where h is Planck's constant and p is the particle's momentum.

9. What is the significance of the Planck length in relation to wavelength?

The Planck length (about 1.6 × 10⁻³⁵ m) is theoretically the shortest meaningful length in physics. It's thought to be the scale at which quantum effects of gravity become significant, and potentially the lower limit for the wavelength of any particle.

10. How does the wavelength of light affect its polarization?

The wavelength of light doesn't directly affect its polarization. Polarization is related to the orientation of the electric field oscillations, which is perpendicular to the direction of wave propagation, regardless of wavelength.

11. What is the relationship between wavelength and the Doppler effect?

The Doppler effect causes a change in the observed wavelength when there is relative motion between the source and observer. If they are moving apart, the wavelength increases (redshift), and if they are moving closer, the wavelength decreases (blueshift).

12. What is the relationship between wavelength and the uncertainty principle?

The uncertainty principle states that the product of uncertainties in position and momentum must be greater than or equal to ħ/2. For light, this translates to a relationship between wavelength uncertainty and position uncertainty: Δx · Δ(1/λ) ≥ 1/4π.

13. How does the wavelength of light relate to its coherence length?

The coherence length of light is related to its spectral width. Monochromatic light (single wavelength) has a long coherence length, while light with a broad spectrum of wavelengths has a short coherence length. This affects the light's ability to produce interference patterns.

14. What is the significance of the Compton wavelength shift?

The Compton wavelength shift occurs when a photon collides with an electron, transferring some of its energy and momentum. This results in an increase in the photon's wavelength, demonstrating the particle nature of light in its interaction with matter.

15. How does the wavelength of light relate to its group and phase velocities?

In dispersive media, the group velocity (velocity of a wave packet) and phase velocity (velocity of a single frequency component) can differ. Both are related to wavelength, but in different ways, leading to phenomena like pulse broadening in optical fibers.

16. What is the relationship between wavelength and the quantum mechanical wave function?

In quantum mechanics, the de Broglie wavelength is related to the wavelength of the wave function describing a particle. The wave function's wavelength determines the probability distribution of finding the particle at different positions.

17. How does the wavelength of light affect its interaction with metamaterials?

Metamaterials are engineered to have properties not found in nature, often by manipulating their structure at scales smaller than the wavelength of light. This allows for unique interactions, such as negative refractive indices or perfect lensing, which depend on the relationship between the material's structure and the light's wavelength.

18. What is the significance of the Bragg wavelength in fiber optic sensing?

The Bragg wavelength is the specific wavelength of light that is reflected by a fiber Bragg grating. It's sensitive to strain and temperature, making it useful for sensing applications. The Bragg wavelength is determined by the grating period and the effective refractive index of the fiber core.

19. What is the relationship between wavelength and the Abbe diffraction limit?

The Abbe diffraction limit sets the minimum resolvable distance in optical systems, given by d = λ/(2n sin θ), where λ is the wavelength, n is the refractive index, and θ is the half-angle of the maximum cone of light entering the lens. Shorter wavelengths allow for better resolution.

20. How does the wavelength of light affect its interaction with photonic crystals?

Photonic crystals have periodic structures on the scale of the wavelength of light. This periodicity creates photonic band gaps - ranges of wavelengths that cannot propagate through the crystal. The interaction depends strongly on the relationship between the crystal's periodicity and the light's wavelength.

21. What is the significance of the Raman shift in terms of wavelength?

The Raman shift is the change in wavelength of inelastically scattered light compared to the incident light. It's typically expressed in wavenumbers (inverse centimeters) and provides information about vibrational, rotational, and other low-frequency modes in a system.

22. How does the wavelength of light affect its interaction with surface plasmons?

Surface plasmons are collective oscillations of electrons at the interface between a metal and a dielectric. Their interaction with light is strongly wavelength-dependent. At specific wavelengths, surface plasmon resonance can occur, leading to enhanced optical fields and absorption.

23. What is the significance of the cutoff wavelength in waveguides?

The cutoff wavelength is the longest wavelength that can propagate in a particular mode in a waveguide. Wavelengths longer than the cutoff cannot propagate and are attenuated. This is important in the design of optical and microwave waveguides and fibers.

24. What is the relationship between wavelength and the Fraunhofer diffraction pattern?

Fraunhofer diffraction occurs when light waves are diffracted in the far field. The resulting diffraction pattern depends on the wavelength of light and the size and shape of the diffracting aperture. The angular position of diffraction minima and maxima is proportional to the wavelength.

25. How does the wavelength of light affect its interaction with quantum dots?

Quantum dots are semiconductor nanocrystals whose optical properties depend strongly on their size. The wavelength of light they absorb or emit is related to their size due to quantum confinement effects. Smaller quantum dots interact with shorter wavelengths of light.

26. What is the significance of the Brewster's angle in relation to wavelength?

Brewster's angle is the angle of incidence at which light with a particular polarization is perfectly transmitted through a transparent dielectric surface, with no reflection. While the angle itself is not directly dependent on wavelength, the refractive indices used to calculate it often have a wavelength dependence.

27. How does the wavelength of light change when it enters a different medium?

When light enters a different medium, its wavelength changes but its frequency remains constant. The wavelength decreases when light enters a denser medium (like water) and increases when it enters a less dense medium (like air).

28. What is the relationship between wavelength and diffraction?

Diffraction is more pronounced for waves with longer wavelengths. When a wave encounters an obstacle or opening, the amount of bending (diffraction) is greater if the wavelength is comparable to or larger than the size of the obstacle or opening.

29. How does the wavelength of light affect its refraction?

Different wavelengths of light refract (bend) at slightly different angles when passing through a medium. Shorter wavelengths (like blue light) refract more than longer wavelengths (like red light), which causes dispersion phenomena like rainbows.

30. How does the wavelength of light relate to its penetration depth in a material?

Generally, longer wavelengths penetrate deeper into materials than shorter wavelengths. This is why radio waves can pass through walls while visible light cannot. However, the exact relationship depends on the material's properties.

31. What is the difference between wavelength and wavenumber?

Wavelength is the distance between two consecutive crests or troughs of a wave, while wavenumber is the number of waves per unit distance. They are inversely related: wavenumber = 1/wavelength.

32. How does changing the wavelength of light affect its scattering?

Shorter wavelengths scatter more than longer wavelengths. This is described by Rayleigh scattering, which is proportional to 1/λ⁴. This explains why the sky appears blue (shorter wavelengths scatter more) and sunsets appear red (longer wavelengths penetrate the atmosphere more easily).

33. What is the relationship between wavelength and the photoelectric effect?

The photoelectric effect depends on the frequency (and thus wavelength) of light. There is a threshold frequency below which no electrons are emitted, regardless of intensity. This threshold corresponds to a maximum wavelength, above which the photoelectric effect does not occur.

34. How does the wavelength of light affect its resolution in imaging?

The resolution of an imaging system is limited by the wavelength of light used. Shorter wavelengths allow for higher resolution because they can distinguish between closer points. This is why electron microscopes (which use electrons with very short de Broglie wavelengths) can achieve much higher resolutions than optical microscopes.

35. How does the wavelength of light affect its absorption by materials?

Different materials absorb light of different wavelengths. This selective absorption is responsible for the colors we see in objects. For example, a red object appears red because it absorbs most wavelengths except red, which it reflects.

36. What is the relationship between wavelength and the wave-particle duality of light?

The wave-particle duality of light means that light exhibits both wave-like and particle-like properties. The wavelength is a wave property, while the associated energy (E = hc/λ) can be thought of as a particle property (photon energy).

37. What is the relationship between wavelength and the speed of light in different media?

The speed of light in a medium is related to its wavelength and frequency by the equation v = fλ, where v is the speed in the medium, f is the frequency, and λ is the wavelength. As the speed changes in different media, the wavelength changes proportionally while the frequency remains constant.

38. How does the wavelength of light relate to interference patterns?

Interference patterns are directly affected by wavelength. The spacing between interference fringes is proportional to the wavelength. Longer wavelengths produce wider fringe spacing, while shorter wavelengths produce narrower spacing.

39. What is the significance of the characteristic wavelength in atomic spectra?

Characteristic wavelengths in atomic spectra correspond to specific electron transitions between energy levels in an atom. These wavelengths are unique to each element, allowing for spectroscopic identification of elements in distant stars or in laboratory samples.

40. How does the wavelength of light affect its reflection?

The wavelength of light doesn't significantly affect its reflection from smooth surfaces. However, for rough surfaces, if the surface irregularities are comparable to the wavelength of light, diffuse reflection occurs, scattering the light in many directions.

41. How does the wavelength of light affect its transmission through optical fibers?

Different wavelengths of light have different transmission properties in optical fibers. Some wavelengths experience less attenuation and dispersion, making them more suitable for long-distance communication. Common wavelengths used are around 850 nm, 1300 nm, and 1550 nm.

42. How does the wavelength of light affect its interaction with nanostructures?

When the size of nanostructures is comparable to or smaller than the wavelength of light, unique optical effects can occur. This is the basis for many nanophotonic devices and phenomena like surface plasmon resonance.

43. What is the significance of the Wien displacement law in relation to wavelength?

Wien's displacement law relates the temperature of a black body to the wavelength at which it emits the most radiation. As the temperature increases, the peak wavelength of emission shifts to shorter wavelengths.

44. What is the relationship between wavelength and the refractive index of a material?

The refractive index of a material generally varies with wavelength, a phenomenon called dispersion. This variation is responsible for the splitting of white light into colors by a prism and is described by the Cauchy equation or the Sellmeier equation.

45. How does the wavelength of light affect its ability to induce chemical reactions?

The wavelength of light determines its energy, which affects its ability to induce chemical reactions. Shorter wavelengths (higher energy) are more likely to break chemical bonds or excite electrons, potentially initiating photochemical reactions.

46. How does the wavelength of light relate to its ability to carry information?

The information-carrying capacity of a light wave is related to its frequency (and thus wavelength) through the Shannon-Hartley theorem. Higher frequencies (shorter wavelengths) potentially allow for higher data rates in optical communication systems.

47. How does the wavelength of light relate to its ability to ionize atoms or molecules?

Ionization occurs when the energy of a photon is sufficient to remove an electron from an atom or molecule. This requires the wavelength to be short enough (frequency high enough) to overcome the ionization energy. For most atoms, this corresponds to ultraviolet or shorter wavelengths.

48. What is the relationship between wavelength and the Talbot effect?

The Talbot effect is a near-field diffraction effect where a periodic pattern repeats at regular distances from the original pattern. The Talbot distance is proportional to the square of the pattern's period and inversely proportional to the wavelength of light.

49. How does the wavelength of light relate to its ability to produce fluorescence?

Fluorescence occurs when a material absorbs light of one wavelength and emits light of a longer wavelength. The absorption wavelength must be short enough to excite electrons to a higher energy state, while the emission wavelength depends on the energy levels of the material.

50. How does the wavelength of light relate to its ability to drive photosynthesis?

Photosynthesis primarily uses light in the visible spectrum, with peak absorption in the blue (around 450 nm) and red (around 650 nm) regions. The wavelength of light determines its energy and thus its ability to drive the photochemical reactions in photosynthesis. Green light (around 550 nm) is less effective, which is why plants appear green.