Fission Chain Reaction

Fission Reaction Chain:

We know that during a fission reaction a nucleus of U-235 absorbs a slow neutron and breaks into of almost equal masses along with the emission of 2 or 3 neutrons. By properly using these neutr reaction can be produced in more Uranium atoms such that a fission reaction can continuously ma This process is called Fission Chain Reaction. There are two types of Fission Chain Reaction. two maintain itself.
. Uncontrolled Fission Chain Reaction:

1 41 when U is bombarded with a slow neutron, then Ba and Kr are formed and three neutrons are emitted. These 3 neutrons cause three more fission reactions in three u atoms and g neutrons are produced These 9 neutrons will cause additional fission. In this way the process multiplies and is called Uncontrolled Fission Chain Reaction as shown in 92 235 92 figure. This is principle of atom bomb. As a result of uncontrolled fission chain reaction in an atom bomb an atomic explosion takes place and a huge amount of energy is released.




 2. Controlled Fission Chain Reaction: 
It is possible to produce such conditions in which only 1 neutron out of all the neutrons produced in one fission, produces further fission. The other neutrons either escape out or are absorbed in some other medium except uranium. Such a reactions is called controlled fission chain reaction and fission reaction proceeds with constant initial speed. 235  a slow neutron is incident on a thin sheet of U.
Fission Takes Place:
Fission takes place but three neutrons produced are scattered into air so no further 92 fission can take place.  only two fission reaction take place. No further fission is possible. Hence, chain reaction is not possible. 235 in Fig. (c) if the sphere of is big one, then most of the neutrons produced due to fission reaction get absorbed in U before escaping out 92 92 of the sphere and produce a chain reaction. Critical Mass: The minimum mass of uranium which can sustain a chain reaction is called the critical mass. Critical Volume: Volume of the critical mass of Uranium is called critical volume. Reaction between Mass of Uranium and Critical Mass: If the mass of uranium is

much greater than the critical mass, then the chain reaction proceeds at a rapid speed and a huge explosion is produced. Atom bomb works at this principle.

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Production of X-Rays

Production of X-Rays:
                                                           

Production of X-Rays:

X-Rays were discovered by Germen physicist. X-Rays have very smaller wave length or high frequency . The production of X-Rays

 is the reverse process of photo electric effect.

X-Rays:

Then fast moving electrons strike  on a metal surface photo of very high energy are emitted known as X-Rays.

Ka Rays:

Suppose that a fast moving electron of energy Ve strike target of tungsten or any other heavy atom . Let an Electron from K-Shell of the atom is Removed it produce a Vacancy of electron or hole in k shell.

The electron from Lshell jumps to occupy the hole there by  the emitting a photon energy.

K         

      B Rays:

It is possible that electron jumps from M- shell in to K- shell. The  Photon emitted with energy.

Biological Effects of X- Rays :

OGICAL EFFECTS OF X-RAY/Side X ( y are Ionizing radiations. They may cause damage to living tissue As always photons are absorbed in tissues they break molecular bonds and  the molecular structure of proteins and especially the genetic y excessive use. Even when the organism itself shows no apparent e highly reactive free radicals (such as H and d rial. Young and rapidly growing cells are sensitive, hence X-fays are  for selective destruction of cancer cells. The X-ray can cause cancer asi se. damage, excessive use may cause the changes in reproductive system that will affect the organism 's offspring ICO' will Production of x rays can be regarded as the inverse of (a) Fair production (b) Compton effect ey Photo electric effect.

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