info@urfaculty.com

www.urfaculty.com

Govt. Job/ Sarkari Naukri, NEET, CAT, Bank Exam & Study materials

Saturday, 11 March 2017

Nuclei - V


Rate of Decay or Activity of a Radioactive Sample:

It is defined as the number of radioactive disintegrations taking place per second in a given sample. It is expressed as,

Curie:
a) It is the SI unit of decay.
b) One curie is the decay rate of 3.7 X 1010 disintegrations per second.

Rutherford:
One Rutherford is the decay rate of 106 disintegrations per second.

Natural Radioactivity:

It is the phenomenon of the spontaneous emission of-a  , b and g  radiations from the nuclei of naturally occurring isotopes.

Artificial or Induced Radioactivity:
It is the phenomenon of inducing radioactivity in certain stable nuclei by bombarding them by suitable high energy sub atomic particles.

Nuclear Reaction:
It is a reaction which involves the change of stable nuclei of one element into the nucleus of another element.

Nuclear Fission:
It is the process in which a heavy nucleus when excited gets split into two smaller nuclei of nearly comparable masses. For example,


Nuclear Reactor:
It is a device in which a nuclear chain reaction is initiated, maintained and controlled.

Nuclear Fusion:
It is the process of fusion of two smaller nuclei into a heavier nucleus with the liberation of large amount of energy.

Critical size and Critical Mass:
a) The size of the fissionable material for which reproduction factor is unity is called critical size and its mass is called critical mass of the material.
b) The chain reaction in this case remains steady or sustained.

Moderator:
a) Any substance which is used to slow down fast moving neutrons to thermal energies is called a moderator.
b) The commonly used moderators are water, heavy water (D2O) and graphite.

Click here to view complete Chemistry Free Study Materials and Notes for NEET Preparation

Click here to view complete Physics Free Study Materials and Notes for NEET Preparation

Click here to view complete Biology Free Study Materials and Notes for NEET Preparation

Click here to take NEET online practice tests by UrFaculty.com

No comments:
Write comments

Hey, we've just updated our test package. Check'it out here - https://goo.gl/r7FuPT
Join Youth Apps