Electromagnetic Waves

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Electromagnetic Waves by Mind Map: Electromagnetic Waves

1. Visible Light

1.1. Visible light waves are the radiation you can see with your eyes. Their wavelengths are in the range of 1/1000 centimeter.

1.2. We see these waves as the colours of the rainbow. Each colour has a different wavelength. Red has the longest wavelength and violet has the shortest wavelength. When all waves are combined together, they are seen as white light.

1.3. Light is used in optical fibres, medical purposes and telecommunications.

2. Properties of E.W.

2.1. They are transverse waves

2.2. Travel at the speed of 3x10^8 m/s

2.3. Exhibit wave properties such as reflection and refraction

2.4. Transfer energy from one place to another

2.5. Do not require medium to travel from one point to another

2.6. They do not carry electric charge

2.7. Their frequencies does not change when they travel from one medium to another

2.8. Equation :

3. Examples of E.W.

3.1. Main components of Electromagnetic sectrum

4. Effects of E.W.

4.1. 1.Infrared Heating

4.1.1. Electromagnetic radiation may cause certain molecules to absorb energy and hence , warm up food in a microwave oven. Similarly, when our skin detects the heat from the radiating charcoal fire that is used to cook food , our skin absorbs the infrared waves that make us feel warm.

4.2. 2.Ionisation and the effects of ionising radiation on living matter

4.2.1. Ionisation refers to the process of ion formation. High energy electromagnetic waves such as UV rays, x-rays are able to ionise atoms and molecules, including living matter.

4.2.2. High energy electromagnetic waves such as xrays and gamma rays are able to to ionise atoms and molecules. excessive exposure to ionising radiation can be harmful to living tissues ; causing sunburn , skin cancer , damage to living cells and tissues, premature aging and shortening of lifespan.

4.2.3. Damage to human body : 1. At the molecular level, irradiation of human tissues may result in damage to proteins, nucleic acids and other vital molecules found in cells. 2. At the sub-cellular level, ionising radiation can cause damage to chromosomes which are structures that bear DNA. 3. A pregnant woman exposing her developing foetus to ionising x-ray imaging runs the risk of giving birth to deformed baby. Ionising radiation may also cause an abnormal pattern of cell division possibly leading to cancers such as leukaemia (cancer of the blood). 4. At the organism level, overexposure to ionising radiation may lead to premature aging and shortening of lifespan.

5. Radio waves

5.1. Radio waves are the longest usable waves, having a wavelength of 1 mile (1.5 kilometer) or more.

5.2. Radio waves are used in radio broadcasting, wireless telegraphy, telephone transmission, television, radar, navigation systems and communications

6. Microwaves

6.1. Longer microwaves are used in telecommunication as well as for cooking food.

6.2. Shorter microwaves are used in remote sensing and satellite televisions.

7. Infrared

7.1. They are barely visible. They are the deep red rays you get from a heat lamp.

7.2. Far infrared wavelengths are about the size of a pin head and the shorter , near infrared wavelengths are the size of cells, or are microscopic.

7.3. Far infrared are thermal. We experience this type of radiation every day in the form of heat.

7.4. Shorter, near infrared waves are not hot at all. In fact you cannot feel even feel them. These shorter wavelengths are the ones used by your television's remote control. They can also be used as intruder alarms.

8. Gamma-rays

8.1. Gamma-rays are dangerous rays coming from nuclear reactors and atomic bombs. They have the shortest wavelength in the electromagnetic spectrum of about 1/10,000,000 centimeter.

8.2. Gamma-rays have the smallest wavelengths . It can kill living cells as such these rays are used to kill cancerous cells in medical treatment.

9. X-rays

9.1. X-rays can pass through soft body tissues easily, but they can also be blocked by hard material such as bones. Thus, if a beam of x-rays passes through your body and is then exposed on a film , a faint outline of your soft tissues will be seen, but your bones will show up distinctly.

9.2. X-rays go through the body and are used for medical purposes. X-rays are also used in commercial airplanes and bridges to make sure that there are no stress fractures or other dangerous cracks in the structures.

10. Ultraviolet

10.1. Ultraviolet rays are invisible to the human eye, however, some insects , like bumblebees, can see them.

10.2. It is also what give you sunburn and are used in "black lights" that make object glow.

10.3. It can be used to remove free floating microscopic water borne bacteria, parasitic, fungal, viral, algae and other unfriendly pathogens in aquarium water. This can also be effective and safe method for water treatment.