বৈদ্যুতিক চৌম্বকীয় বর্ণালী

• The electromagnetic spectrum is the complete range of electromagnetic radiation.
• Radiation is energy that travels and spreads out as it propagates.
• Visible light that comes from a lamp and radio waves that come from a radio station are types of electromagnetic radiation.
• Other types of electromagnetic radiation are microwaves, infrared light, ultraviolet light, X-rays and gamma rays.

Properties

• Electromagnetic radiation can be described in terms of a stream of mass-less particles, called photons, each traveling in a wave-like pattern at the speed of light.
• Each photon contains a certain amount of energy.
• The different types of radiation are defined by the the amount of energy found in the photons.
• Radio waves have photons with low energies, microwaves have more energy than radio waves, infrared has still more, then visible, ultraviolet, X-rays, and, the most energetic of all, gamma-rays.
• Electromagnetic radiation can also be described in terms of wavelength and frequency.
• The wavelength is the distance between crests of a wave.
• The frequency is the number of crests that pass a given point within one second.
• Wavelength and frequency are inversely proportional: as the wavelength decreases, the frequency increases.
• The different types of electromagnetic radiation can also be defined by their wavelength and frequency.

Regions of the Electromagnetic Spectrum

• The electromagnetic spectrum is generally divided into seven regions, in order of decreasing wavelength and increasing energy and frequency.
• The common designations are: radio waves, microwaves, infrared (IR), visible light, ultraviolet (UV), X-rays and gamma rays.

Radio waves

• Radio waves have wavelengths ranging from millimeters to hundreds of kilometers.
• They are used for broadcasting, communications, radar and other applications.

Microwaves

• Microwaves have wavelengths ranging from about a millimeter to a meter.
• Microwaves are used for cooking, communication, and radar.
• They are also used in microwave ovens to heat food by causing water molecules to vibrate.

Infrared

• Infrared radiation has wavelengths ranging from about 700 nanometers to 1 millimeter.
• Infrared radiation is often associated with heat.
• Infrared is used in thermal imaging, remote controls, and industrial heating.

Visible light

• Visible light has wavelengths ranging from about 400 to 700 nanometers.
• It is the only part of the electromagnetic spectrum that is visible to the human eye.
• The different colors of visible light correspond to different wavelengths, with violet having the shortest wavelength and red having the longest.

Ultraviolet

• Ultraviolet radiation has wavelengths ranging from about 10 to 400 nanometers.
• UV light can cause sunburns and skin cancer.
• It is also used in sterilization and tanning beds.

X-rays

• X-rays have wavelengths ranging from about 0.01 to 10 nanometers.
• X-rays can penetrate soft tissues, so they are used in medical imaging.
• They are also used in industrial radiography.

Gamma rays

• Gamma rays have the shortest wavelengths and highest energy of all electromagnetic radiation.
• Gamma rays are produced by nuclear reactions and radioactive decay.
• Gamma rays are used in cancer treatment and sterilization.

Applications of the Electromagnetic Spectrum

Communication

• Radio waves and microwaves are used for wireless communication, including cell phones, radio, and television.
• Infrared radiation is used in remote controls and short-range wireless communication.

Medicine

• X-rays are used for medical imaging, such as radiography and computed tomography (CT) scans.
• Gamma rays are used in radiation therapy to treat cancer.
• Infrared radiation is used in thermal imaging to detect temperature variations in the body.

Industry

• Microwaves are used for heating and drying materials in industrial processes.
• Infrared radiation is used for industrial heating and drying.
• X-rays are used for industrial radiography to inspect welds and other materials.
• Gamma rays are used for sterilization of medical equipment and food.

Science

• The entire electromagnetic spectrum is used in astronomy to study the universe.
• Radio waves are used to study the cosmic microwave background radiation.
• Infrared radiation is used to study the composition and temperature of stars and planets.
• Visible light is used to study the surfaces of planets and moons.
• Ultraviolet radiation is used to study the atmospheres of stars and planets.
• X-rays and gamma rays are used to study black holes and other high-energy phenomena.

Safety

• While electromagnetic radiation has many beneficial applications, it can also be harmful to humans.
• Exposure to high levels of UV radiation can cause sunburn, skin cancer, and cataracts.
• Exposure to high levels of X-rays and gamma rays can cause radiation sickness and cancer.
• Exposure to high levels of microwaves can cause burns.
• It is important to take precautions to protect yourself from harmful electromagnetic radiation.
• This includes wearing sunscreen, limiting exposure to UV radiation, and avoiding unnecessary X-rays.