What is Monochromatic Light?
Light is the key wellspring of energy on Earth. Light is of different wavelengths grouped in view of its properties and behaviour. Light shows different properties like Diffraction, Reflection, Refraction, Polarisation, and Interference. Electromagnetic radiations comprise different wavelengths of light.
Innovations using monochromatic light have an extensive variety of applications, from astronomy and astrophysics to forensic science. To answer the question of what is monochromatic light or monochromatic light definition, let’s understand the term itself. The term monochromatic comes from the Greek words monos, meaning one or single, and chromos, meaning colour. Monochromatic light, or one-variety light, is basically electromagnetic radiation gotten from photon discharges from atoms. Photons engender, or travel, as energy wave fronts of various lengths and levels of energy. Energy levels decide the recurrence of light, and the length of a wave decides its colour. The groups of light frequencies that people can see are called visible light.
Theodore Maiman
Theodore Harold Maiman, an American engineer and physicist (July 11, 1927-May 5, 2007), is widely recognised as the father of the laser. Numerous more kinds of lasers were later developed as a result of Maiman's laser. On May 16, 1960, the laser was successfully fired. Maiman and his employer, Hughes Aircraft Company, introduced the laser to the world on July 7, 1960, in Manhattan.
Theodore Maiman
Source of Monochromatic Light
Lasers are an essential source of monochromatic light. As opposed to narrow-band light obtained by bandpass filtering light from a broadband source, lasers can create semi-monochromatic light with high optical powers. A few lasers even show outrageous levels of monochromaticity, i.e., a tiny optical bandwidth. The most significant level of monochromaticity is accomplished with carefully balanced out single-frequency lasers.
The antonym of monochromatic is polychromatic. A normal model for polychromatic light is life made as thermal radiation, for example in an incandescent light; such light shows an expansive scope of optical frequencies.
Numerous computations in optics and photonics are performed for monochromatic light. For instance, the development of laser radiates is generally determined that way; there is only one given optical frequency or wavelength.
Monochromatic light can be separated from polychromatic light utilising a monochromator. Before the approach of the laser, delivering monochromatic light was very difficult. One chance was to utilise certain gas-release lamps and metal vapour lamps (for example, mercury vapour lamps and sodium vapour lamps), emanating light predominantly in specific narrow spectral lines and isolating one such line with a reasonable monochromator. The accomplished optical powers and intensities were very low.
A monochromator is basically a sort of optical channel which permits one to separate light in a narrow spectral interval from other light. Its result will be quasi-monochromatic. Nevertheless, the light at any remaining frequencies is then lost.
Properties of Monochromatic Light
Now, let us study a few important properties of monochromatic light.
Monochromatic light is made up of a relatively small bandwidth of wavelengths.
The intensity of monochromatic light is extremely high.
Because monochromatic light is coherent, it is focused in a very narrow area, and can not be spread apart from the point of focus.
In a straight line, monochromatic light can travel incredibly vast distances.
Since the light has a relatively small wavelength bandwidth, monochromatic light appears as a single colour in the visible region.
The energy of monochromatic light is extremely high.
Types of Monochromator
Prism monochromator
Grating monochromator
In prism monochromators, a prism is utilised as a dispersive component, and in grating monochromators, a reflecting diffraction grating is utilised as a dispersive component.
Monochromatic Light Examples
There exist different monochromatic sources of light in our day-to-day routine. Some of them are recorded beneath:
LASER is an abbreviation for light intensification by stimulated emission of radiation. A LASER light delivers a profoundly directional, single-coloured, and intense light emission. Generally, LASER radiates are red, green, or blue in variety.
Sodium light is normally light golden yellow in variety and is one of the most mind-blowing examples of monochromatic light utilised in our regular routine.
The light transmitted by a light-emitted diode(LED) is regularly monochromatic in nature as it doesn't contain photons that have a place with various wavelength bands.
A spark lamp is one of the most mind-blowing examples of monochromatic sources of light. They normally utilise a LED bulb to create light radiations into the environment.
Applications of Monochromatic light
Ultraviolet monochromatic gadgets are utilised in crime scenes to discover explicit and sensitive proof. Monochromatic light assists with perceiving hidden bloodstains, fingerprints, and sores under the skin.
The holograms engraved on credit cards, money notes, and different records are generally made with the help of monochromatic laser lights. Likewise, 3D holograms normally are shown with the help of monochromatic light beams.
Summary
Monochromatic light has definitively only one frequency, yet practically speaking this is not possible, and thus monochromatic light generally comprises a (little) bandwidth of wavelength. If monochromatic light is in the visible spectrum, the colour that can be seen by the natural eye is known as spectral colour.
A monochromator secludes monochromatic light from a broadband light source; lasers create monochromatic light directly. The monochromatic word comes from Greek where monos means single and chromos means colour. So, monochromatic light is a single wavelength light. The main source of monochromatic light is a Laser beam. Before the approach of the laser, monochromatic light can be separated from polychromatic light utilising a monochromator. Monochromatic lights are used in forensics to scan bloodstains, fingerprints, and so on.
FAQs on Monochromatic Light
1. What is monochromatic light and how is it different from polychromatic light?
Monochromatic light consists of electromagnetic waves of a single wavelength or frequency, resulting in light of only one colour. In contrast, polychromatic light contains multiple wavelengths, combining several colours, as seen in sunlight or white LED lights.
2. How is monochromatic light produced in a laboratory setting as per the Physics syllabus?
Monochromatic light in laboratories is commonly produced using lasers and monochromators. Lasers generate intense, coherent, nearly single-wavelength light directly. Monochromators separate a narrow wavelength band from a broad spectrum light source using prisms or diffraction gratings.
3. What are the key properties of monochromatic light that make it important in Physics experiments?
- Narrow bandwidth: Consists of a small range of wavelengths.
- High intensity: Especially with laser sources.
- Coherence: The waves remain in phase, facilitating interference and diffraction studies.
- Directional: Travels in straight lines with minimal spread.
4. Why is laser considered a highly efficient source of monochromatic light?
Lasers are highly efficient because they emit coherent, intense, and nearly single-wavelength light. This makes them ideal for applications like optical experiments, medical procedures, and fiber-optic communications, which require precision and minimal wavelength variation.
5. How does a monochromator work to isolate monochromatic light from a polychromatic source?
A monochromator uses dispersive components, such as a prism or a diffraction grating, to separate and transmit only a narrow band of wavelengths from a broad-spectrum light source, blocking or discarding all other wavelengths.
6. Can you give examples of monochromatic light sources used in daily life and scientific research?
- Lasers: Used in laboratories, CD/DVD players, laser pointers, and medical devices.
- Sodium vapor lamps: Commonly used in street lighting, emitting yellow monochromatic light.
- LEDs: Single-colour LEDs emit nearly monochromatic light, useful in displays and indicators.
7. What are some real-world applications of monochromatic light according to the NCERT Physics curriculum?
Monochromatic light is crucial in interference and diffraction experiments, spectroscopy, fiber-optic communication, and forensic analysis (such as detecting hidden bloodstains or fingerprints under ultraviolet monochromatic light).
8. How does monochromatic light contribute to the study of interference and diffraction?
Interference and diffraction patterns are clearer and more pronounced with monochromatic light because all waves have the same wavelength and phase relationship, resulting in stable and easily observable fringe patterns required for Physics experiments.
9. Why is it necessary to use monochromatic light in spectrophotometry?
In spectrophotometry, monochromatic light is essential for accurately measuring the absorption or transmission of specific wavelengths by a material, helping to determine the concentration of substances in a solution.
10. What misconceptions do students often have about monochromatic light?
One common misconception is believing monochromatic light always means visible and coloured light; however, it can be ultraviolet or infrared as well. Additionally, some students think that monochromatic sources are perfectly pure; in reality, even laser light has a narrow but finite bandwidth.
11. How did Theodore Maiman contribute to the development of monochromatic light sources?
Theodore Maiman is credited with inventing the first functional laser in 1960, which produced intense, coherent, and nearly monochromatic light, revolutionising both scientific research and practical applications.
12. What would happen if a white light source is mistakenly used instead of monochromatic light during Young’s double-slit experiment?
If white light is used, the interference fringes become blurred or form coloured patterns, making it difficult to obtain clear, distinct fringes. Monochromatic light yields sharp, uniform fringes, simplifying accurate measurement of fringe spacing.
