Saturday, 20 July 2013

Types of Radiations

This chapter deals with types of Radiations based on wavelength, if you know the types of radiations you may skip this chapter.

Radiations can be classified into various kinds depending upon the frequency (or wavelengths) of the radiation and particles present in the radiation.

Some of them are :

Radio Waves : The wavelength of radio waves vary from 10 to 108m. This is done so that it can penetrate easily through the Earth's atmosphere. To create such long waves astronomers use telescopes with huge antennas. They are invisible with naked eye. FM radio waves are however shorter for clarity.

Microwaves : Microwaves have a wavelength of 1cm to 1 micro meter. They can penetrate Earth's atmosphere and have better signal quality and sharpness. They are used to transmit electronic data from one part of earth to another. They are also invisible with naked eye.

Infrared : Infrared Radiations have a wavelength of 10-6 to 10-4m. They are visible to naked eye but they are so intense that they can damage Human eye. Sun Light contains Infrared Radiations but a few of them can only penetrate Earth's atmosphere.

Visible light : Visible light or simply light have a wavelength ranging from 400 to 750 nm. This a narow range of radiations which is visible to us.

Ultra Violet rays : After the visible light the radiations of shorter wavelengths are called rays. UV rays have a range of 10-8m to 10-7 m wavelength. They have high frequency due to which they are unable to penetrate Ozone Layer. They can very easily damage Human eye.

X-rays : X-rays are very powerful rays. They can even penetrate conventional mirrors. They have very short wavelength (~0.1 nm). They are produced when electrons hit a dense metal anode (Positive plate of a electrical circuits). They are not deflected by magnetic or electrical fields.

Radioactive rays : Most X-rays are produced when an electron strikes a metal anode but their there are few elements which emit radiations on their own. Such elements are called Radioactive elements. There are three types of Radioactive rays on the basis the particles in them :

Alpha Rays : They contain high energy particles carrying two units of positive charge and four units of atomic mass, i.e they contain particles of Helium nuclei (as Helium nuclei also contain two protons and two neutrons resulting in 4 atomic mass).

Beta Rays : They contain negatively charged particles, mostly electrons. They are 100 times more powerful than Alpha rays.

Gamma Rays : They are high energy radiations like X-rays and do not contain any particle, i.e they are neutral in nature. They are 10 times more powerful than Beta Rays.

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