- Electromagnetic waves or EM waves are waves that are created as a result of vibrations between an electric field and a magnetic field.
- In other words, EM waves are composed of oscillating magnetic and electric fields.
- Electromagnetic waves are formed when an electric field comes in contact with a magnetic field. They are hence known as 'electromagnetic' waves.
- The electric field and magnetic field of an electromagnetic wave are perpendicular (at right angles) to each other. They are also perpendicular to the direction of the EM wave.
Electromagnetic Spectrum:
- Electromagnetic radiation is one of the many ways that energy travels through space.
- The heat from a burning fire, the light from the sun, the X-rays used by your doctor, as well as the energy used to cook food in a microwave are all forms of electromagnetic radiation.
- While these forms of energy might seem quite different from one another, they are related in that they all exhibit wavelike properties.
- Electromagnetic waves can be classified and arranged according to their various wavelengths/frequencies, this classification is known as the electromagnetic spectrum.
- The following table shows us this spectrum, which consists of all the types of electromagnetic radiation that exist in our universe.
Radio Waves:
- Stars and lightning are natural sources of radio waves, but these are also produced by the antenna on a radio transmitter. They are used to transmit television.
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| Used For Communication Purpose |
Micro Waves:
- Microwaves with certain wavelengths are absorbed by water molecules and can be used for cooking. Water in the food absorbs the microwave radiation, which causes the water to heatup and cook the food.
- Microwaves are also used for point-point communication.
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| Used in Microwave Ovens |
Infrared Waves:
- Since the primary source of infrared radiation is heat or thermal radiation, any object which has a temperature radiates in the infrared.
- The main technology used in home remote controls is infrared (IR) light. The signal between a remote control handset and the device it controls consists of pulses of infrared light, which is invisible to the human eye.
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| Used for TV Remote Control |
Visible Light:
- Our eyes detect visible light. Fireflies, light bulbs, and stars all emit visible light.
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| Light Emitted from Bulbs,Stars and Firefiles |
UV Rays:
- Sunlight is the greatest source of UV radiation. Man-made ultraviolet sources include several types of UV lamps, arc welding, and mercury vapour lamps.
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| Source of UV Rays |
X-Rays:
- X-rays are a very energetic form of electromagnetic radiation that can be used to take images of the human body.
- This is because different tissues absorb different amounts of radiation. Calcium in bones absorbs X-rays the most, so bones look white.
- Fat and other soft tissues absorb less, and look gray.Air absorbs the least, so lungs look black.
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| Used for X-Ray Purpose |
Gamma-Rays:
- Gamma rays have the smallest wavelengths in the electromagnetic spectrum.
- Gamma rays are often produced in regions of extremely high temperature.
- Gamma rays come from solar flares (eruptions on the sun's surface), pulsars (rotating objects which regularly emit radiation), nova and super nova explosions (explosions that cause stars to become extremely bright).
- Gamma rays can be used to treat certain types of cancers, using a process called radiotherapy.
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| Source of Gamma rays |
