what's nuclear energy and radioactivity and matters related to that. plz explain in brief?

Answer 1

The most common application of nuclear energy is through atomic fission, when the nuclei of atoms with a high "atomic number" split. This forms new elements with lower "atomic numbers" and releases energy and some nuclear, or sub-atomic particles (usually neutrons). This release of energy and particles is called radioactivity. The energy and particles cause other atoms to split and the process continues in what is called a chain reaction.
How this reaction is perceived depends on how fast it proceeds. Slowly, as in a reactor, and you get heat that is used to create steam which spins electrical generators. A rapid chain reaction creates an explosion, an atomic bomb.
In addition, when non-radioactive atoms are subjected to radioactivity, they can become radioactive as well. This is one way that radioactivity can be used for medicinal purposes.
This is just a thumbnail answer to a varied and complex subject. I suggest research from an encyclopedia or related texts.

Answer 2

http://www.colorado.edu/physics/2000/index.pl explore this Rohit.
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