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 :
4.2.3.1. 1. At the molecular level, irradiation of human tissues may result in damage to proteins, nucleic acids and other vital molecules found in cells.
4.2.3.2. 2. At the sub-cellular level, ionising radiation can cause damage to chromosomes which are structures that bear DNA.
4.2.3.3. 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).
4.2.3.4. 4. At the organism level, overexposure to ionising radiation may lead to premature aging and shortening of lifespan.