Electomagnetic Waves
by Sheikh Khairul Ikhwan
1. Sources of EM waves (part 2)
1.1. Visible light is emitted from hot bodies like the sun to produce white light, comprising of the colour spectrum.
1.1.1. Task 1
1.1.2. Task 2
1.2. Infrared radiation is emitted from warm bodies such as fire and ordinary light bulbs or even the sun.
1.3. Microwaves are produced by special electronic devices like klystron(input).
1.4. Radio waves are produced by electrons oscillating in electrical units.
2. Components of spectrum
2.1. Gamma rays
2.1.1. Shortest wavelength
2.1.2. Highest frequency
2.2. X-rays
2.3. Ultra-violet rays
2.4. Visible light
2.5. Infrared Radiation
2.6. Microwave
2.7. Radio Waves
2.7.1. Longest wavelength
2.7.2. Lowest frequency
3. Application of EM waves
3.1. Gamma rays are used to sterilise medical instruments or kill cancerous cells. However, they are very energetic and may ionise living cells in body.
3.2. X- rays are used for medical diagnosis as they penetrate human flash to identify bone structure, though over-exposure may cause cancer cells. X-rays are also used for engineering purposes to check for flaws in metallic joints for industrial usage.
3.3. UV rays produce suntan, kills bacteria and to check for counterfeit notes. They can also cause harm to living tissue, resulting in sunburn or even skin cancer under over-exposure.
3.4. Visible light is used in optical fibres which can be used for data transmission and also lasers for medical surgeries.
3.5. Infrared radiation is used in household electrical appliances, television controllers and also intruder alarms. All objects with temperatures above zero Kelvin will emit infrared radiation (the higher the temperature, the more radiation emitted).
3.6. Microwaves can be used for communications, carrying telephone calls as they pass through atmosphere without much attenuation. It can also be used to heat food as energy carried by waves are strongly absorbed by water molecules.
3.7. Radio waves are used for radio and television communication.
4. Sources of EM waves (part 1)
4.1. Gamma rays are emitted from radioactive substances and nuclear reactions.
4.1.1. Task 1
4.1.2. Task 2
4.2. X rays are produced by hitting high-energy electrons onto particles such as atoms in metals.
4.3. UV rays is emitted from very hot bodies such as the sun and some mercury lamps.
5. What is it?
5.1. Waves that do not require medium to travel
5.1.1. Meeting 1
5.1.2. Meeting 2