Light Energy is a type of energy that is visible to the human eye. Light Energy that reaches us is in the form of a wave. The Light Energy Wave is an Electromagnetic Wave and is transverse in nature. The wavelength of Light Energy Wave is in the range of 400nm to 700nm. Light Energy is reflected from any surface and then enters into our eyes forming the image on the retina to make the object visible.
Like any other form of energy, Light is also a form of energy that can do work. The work done by Light is evident from the photoelectric effect. We have to study Light Energy in Physics Class 10. In this article, we are going to discuss what is Light Energy, the properties of Light Energy, the nature of light energy, and the applications of Light Energy.
What Is Light Energy?
Radiant energy, also known as light energy, is a type of electromagnetic energy that travels in waves and can move through empty space. The energy of Light is a visible form of energy that encompasses a wide range of energy, including ultraviolet (UV), infrared (IR), radio waves, microwaves, X-rays, and gamma rays, in addition to the visible spectrum. The presence of light energy makes it possible for human eyes to see different types of light.
Electromagnetic radiation which is emitted by hot objects such as light bulbs, lasers, and the sun is what defines light. Photons which are essentially tiny packets of energy are present in light. When atoms in an object are heated, photons are produced as a result. Electrons in the atoms gain more energy from the heat which is then released in the form of a photon. The more heat is applied, the more photons are produced.
Propagation of Light Energy
Unlike sound waves which require a medium to travel through, light can travel through space without any medium. This is because light doesn't require any matter to travel with it. The speed of light is very fast and it is the fastest thing known to man. The speed of light is equal to 186,282 miles per second.
Nature Of Light Energy
Light energy is a form of electromagnetic radiation that can be seen by the human eye. Light energy is composed of very small particles called Photons. These photons don't contain any charge on them. The sun releases a vast amount of electromagnetic radiation, out of which only a small fraction is visible to humans and is known as 'visible light.' The movement of solar energy is expressed in wave form, and scientists can determine the energy of a wave by calculating its wavelength and the distance between successive points of a wave (from crest to crest and trough to trough).
The electromagnetic spectrum is the range of all possible radiation frequencies, which includes various kinds of electromagnetic radiation from the sun, such as ultraviolet rays and X-rays. Different types of radiant energy from the sun have been distinguished within the electromagnetic spectrum, and the difference in wavelengths indicates the amount of energy they carry.
Light Energy Formula
Light is a form of energy which is essentially an electromagnetic wave. Hence, the formula used to calculate the energy of an electromagnetic wave is only used to calculate the value of Light Energy. The formula of energy for Light is given as
Energy = hν = hc/λ
where,
- h is Planck's Constant
- ν is Frequency of Light = c/λ
Units of Light Energy
Light energy can be measured using different types of units.
- Angstrom and nanometers are used to calculate the wavelength of light.
- Hertz units calculate the frequency of light energy.
- Electron volts (eV) is the unit to calculate Light energy.
Types of Light Energy
Light energy is of various types. They are:
- Visible Light
- Infrared Light
- X-Ray Light
- UV Light
Let's learn about these forms of light energy in detail
Visible Light
Visible form of Light Energy can only be seen through naked eye. It is a type of electromagnetic energy. The source of visible light is the sun. It can be radiated from flashlights, light bulbs, etc.
Wavelengths of visible light range from approximately 400 to 700 nanometers (nm), with specific wavelengths associated with different colors of light. The shortest wavelength is associated with violet light, while the longest is associated with red light. Frequencies of visible light range from about 430 THz (terahertz) for violet light to 750 THz for red light. Visible light is the portion of the electromagnetic spectrum that can be detected by the human eye.
Visible Light Energy is composed of a spectrum of colors, each of which corresponds to a specific wavelength and frequency. The colors in this spectrum are often represented by the acronym "ROYGBIV" for red, orange, yellow, green, blue, indigo, and violet. Applications are human vision, photography, etc.
Infrared Light
Infrared Light Energy is also a kind of electromagnetic energy that produces heat. TV remotes are a good example of putting the infrared light into effect.
Infrared light has longer wavelengths than visible light, usually between 700 nm and 1 mm. Infrared frequencies range from about 300 GHz to 430 THz. Infrared radiation is mainly linked to heat, as objects emit it through the thermal motion of their molecules. Its applications are thermography, night vision, remote sensing, etc.
X-Rays
Doctors utilize short light waves to capture images inside our bodies and identify bone fractures. Additionally, dentists use x-rays to monitor the progression of tooth decay.
The wavelengths of X-rays are generally shorter, typically falling within the range of 0.01 nm to 10 nm. X-rays have frequencies that range from 30 petahertz (PHz) to 30 exahertz (EHz). X-rays are classified as highly energetic electromagnetic waves and are utilized for their ability to pass through objects. They can travel through soft tissues, but when it comes to denser materials like bones and metals, they are absorbed.
Ultraviolet Light
UV light has wavelengths that are shorter than those of visible light, usually between 10 nm and 400 nm. UV frequencies range from 800 THz to 30 PHz. UV radiation is a constituent of sunlight and is capable of causing harm to living beings, such as DNA mutations and skin burns.
Properties of Light Energy
The properties of Light Energy is well described on the basis of different parameters. The properties of energy of Light based on the different parameters is mentioned below:
- Intensity: Intensity of light refers to the amount of light energy emitted by a source per unit time, measured in watts. It can also be described as the level of brightness produced by light in a given area per unit time or energy per unit area.
- Frequency: Frequency of Light on the other hand, refers to the number of wave crests that pass through a particular point in one second.
- Wavelength: Wavelength of light is the distance between two adjacent crests or troughs. It is worth noting that all light waves travel at the same speed through a vacuum. Additionally, wavelength and frequency are closely related, with higher frequencies corresponding to shorter wavelengths.
- Polarizatiuon: Polarization of Light is the process by which unpolarized light is transformed into polarized light. Unpolarized light consists of waves vibrating in multiple planes.
- Phase: Phase of Light refers to a specific point in the cyclic waveform's timeline. When waves are in phase, the intensity of light energy increases.
Applications of Light Energy
Light Energy is a form of electromagnetic radiation that can be seen by the human eye. But there are also many commercial and scientific uses of light energy, some of which are listed below.
- All living organisms rely on light as the sole source of food generation. With the exception of some chemotrophic organisms such as bacteria, all organisms require light for energy and sustenance.
- While eyes allow organisms to view the world around them, they are rendered useless without the presence of light. When light falls on the eyes, they receive an image which is transmitted to the brain, allowing organisms to perceive their surroundings.
- Light is composed of a range of spectra, each with its own individual colour, collectively referred to as VIBGYOR.
- UV Light is used as disfectant and for cleaning purpose due to high energy.
- IR Light is used to generate heat and in tv remotes for communication.
- Light Energy are used to produce electricity with the help of photovoltaic cells
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