Electro-magnetic Waves

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Electro-magnetic Waves by Mind Map: Electro-magnetic Waves

1. Properties

1.1. They are tranverse waves.

1.2. They do not need a medium to propagate.

1.3. They travel at a constant speed of 3.0 x 10^8 m/s.

1.4. They obey the laws of reflection and refraction.

1.5. They obey the general wave equation of c=fλ and c=λ/T, where c is the speed of light

2. Electromagnetic Spectrum

2.1. It consists of electromagnetic waves of a continuous range of frequencies, such as

2.1.1. Radiowaves Radio broadcasting, telephone, elevision, radar and a lot more.

2.1.2. Microwaves Heat food up by causing the water molecules to vibrate.

2.1.3. Infrared Remote controllers

2.1.4. Visible Light Needed to see things

2.1.5. Ultra-violet rays Used as sun bed for artificial tanning. Lamps that emit strong UVB and UVC radiation are commonly used as germicidal lamps for sterilisation in hospitals

2.1.6. X-rays Can be used to diagnose the fracture of a broken arm. It can penetrate all types of material except lead

2.1.7. Gamma rays Can be used to destroy cancer cells.

2.2. The higher the frequency, the lower the wavelength, and vice versa. In addition, the higher the frequency, the greater the amount of energy carried by the electromagnetic wave.

3. What are they?

3.1. They are non-mechanical and tranverse waves.

3.2. They consist of electric and magnetic fields which oscillate perpendicularly to each other

4. Effects of these waves

4.1. Infrared Heating

4.1.1. For example, we feel the heat from a barbeque pit. The radiant heat we feel is actually infrared in nature. Even though our eyes detect the red colour of the charcoal, it is our skin that absorbs the infrared waves. Hence, making use feel warm

4.2. Ionisation and its effects on living matter

4.2.1. Ionisation refers to the process of ion formation. High energy electromagnetic waves are able to ionise atoms and molecules.

4.2.2. It can cause damage to the human body after prolonged exposure, such as May result in damage to protiens, nucleic acid and other vital molecules in cells. Can damage chromosomes, which are structures of DNA A pregnant women mifhr give birth to a deformed baby. Can cause abnormal pattern of cell division possibly leading to cancer. Such as leukamia May lead to premature aging and shortening of lifespan