There are many types of electromagnetic waves that can be found all over this universe. Some waves are very much powerful whereas some waves are weak. Some of the strong electromagnetic waves are Gamma Ray, X-Ray, Ultraviolet Ray etc. and some of the weak electromagnetic waves are Infrared Ray, Radio Wave etc. According to the strength of such waves, they are used in various works. A list of electromagnetic waves with their area of application are described below:
1. Gamma Ray: Gamma rays have high penetrating capacity. Due to this reason, they are used for killing harmful germs, bacteria, sterilizing of medical instruments and to kill cancer cells inside the body (by radio therapy). These rays are produced from radioactive elements and are harmful on exposure. So, gamma rays can be termed as dangerous electromagnetic waves.
2. X-Ray: X-Rays have less penetrating capacity than gamma rays, so they can pass through muscle and skin but can’t pass through bones, stones, bullets and diseased tissues. So, they are used to detect the presence of bullet or stone or tumors inside the body. It is also used to locate the fractured or broken part of bone in the body. X-Rays are produced when very fast moving electrons are stopped by a heavy type of metal. Much exposure to X-Ray may result to cancer, so it is harmful.
3. Ultraviolet Ray: Ultraviolet rays are produced by carbon arc lamp, electric spark, discharge tube, mercury vapour lamp, hot bodies and the sun. Low concentration of UV light kills germs, converts ergosterol found in our skin, into Vitamin D. They are also useful in the formation of ozone layer, which is the protective layer in the atmosphere. It is also used in burglar alarm, automatic door openers etc. The atom of some substances convert UV light into visible light. Such substances are called fluorescent substances and the process is called fluorescence. Fluorescent powder in mercury lamp converts UV light into visible light. Excess concentration of UV rays can destroy the retina and make a person blind. It may even burn our skin which may peel off making severe wounds. It may result to skin cancer too.
4. Visible Light: Visible light are the electromagnetic waves which can be detected by the eyes of the living beings. They are produced by hot objects and the sun. They are used for lighting and green plants use visible light for their food making process known as photosynthesis.
5. Infrared Rays: Infrared rays are also called heat rays. These rays are produced from hot bodies such as the sun, heaters etc. They are used for cooking, drying, infrared photography etc. Infrared is not scattered by mist of haze in the air so that a clear photograph of objects at considerable distance can be obtained easily. So, this technique is much suitable for photography in foggy areas. These days, infrared photographs are taken by using thermograph. Such photographs are used to determine the variations in the temperatures. When a body absorbs infrared rays, it gains heat energy and becomes hot.
6. Microwave: Like ultraviolet rays, microwaves are also produced from the hot bodies, microwave ovens etc. They are used for heating, cooking as well as for satellite television, communication and radar. Radar system uses these waves to detect the direction and distance of the object.
7. Radio Waves: Radio waves are one of the widely used and well known electromagnetic waves. These waves are produced by radio transmitters, TV Transmitters, radars etc. They are used for transmitting radio, television programme and for communication. The antenna of radio and television absorbs the radio wave energy and then converts them into electrical energy. This electric energy is then converted into sound and light energy. The earth’s atmosphere has electrically charged layers which reflect the radio waves towards the earth. Most of the radio stations use radio waves of wavelengths of 11 to 120m. These are short waves. Ultra High Frequency (UHF) and Very High Frequency (VHF) radio waves have shorter wave lengths. They are not reflected by the layers of atmospheric air. They are slightly diffracted by hills. FM systems use this frequency to transmit sound waves.