PGTRB:LATEST STUDY MATERIALS:
PHYSICS:
NUCLEAR PHYSICS.
- Neutrons and protons are present in the nucleus. It is charged positively.
- Isotopes are the atoms of the same element having the same number of protons but different number of neutrons.
- The higher the binding energy per nucleon the more stable is the nucleus.
- Neutrons and protons are collectively called nucleons.
- The unit of radiation is Roentgen.
- In natural radio activity only Alpha, Beta, and Gamma rays are emitted.
- But in artificial radio activity particles like electrons, neutrons, positrons and Gamma rays are liberated.
- Radio isotopes have a wide application in the field of Agriculture, Medicine and Biology.
- Cyclotron is one of the accelerators to accelerate charged particles.
- To compare the radio activities of elements, the half life period and mean carbon dating.
- Neutron was discovered by Chadwick.
- The neutrons are neutral particles. They cannot be deflected by electric or magnetic field.
- Slow neutrons are called thermal neutrons and are used in fission reaction.
- Nuclear forces are the enormous forces so far discovered.
- The working principle of atom bomb is nuclear fission.
- The working principle of hydrogen bomb is nuclear fusion.
- The hydrogen isotopes are involved in nuclear fusion reaction in hydrogen bomb. hence the name hydrogen bomb.
- Fusion requires a high temperature whereas fission takes place at normal temperature.
- Nuclear fusion takes place in sun and stars because high temperature are available there.
- Uncontrolled chain reaction takes place in Atom whereas controlled chain reaction takes place in nuclear reactor.
- In a hydrogen bomb Uncontrolled nuclear fusion reaction takes place.
- Cosmic rays are ionizing radiations showering on earth all the time coming from outer space.
- The intensity of cosmic rays will changed both with altitude and latitude.
- The process in which a particle and its antiparticle combine to yield new particle is called annihilation of matter.
- Photons, leptons, mesons, baryons and hyperons and neutrino are the various group of elementary particle.
- Energy equivalence to 1 amu is 931 Mev.
- BE/A curve shows that iron nucleus is stable.
- Cobalt 60 is used for the treatment of cancer.
- Atomic number is increased by one in Beta decay.
- To evaluate the ages of ancient object the following method is adopted Radio carbon dating.
- One of the particle accelerator Cyclotron
- Neutrons are neutral particles.
- Neutrons with energies between 0.5 MeV to 10 MeV are called fast neutrons.
- To control the chain reaction the following rods are used in a nuclear reactor cadmium rods.
- In pair production the following pairs are formed electrons and positrons.
- A nuclear reactor is a device in which the nuclear reaction is carried on as perfectly controlled chain reaction in a self sub stained manner.
- The fissionable material or the nuclear fuel is generally 92U235. In some reactors Plutonium-239 is also used.
- Materials like cadmium or Boron are very good absorbers of neutron and are used o control the chain reactions.
- A material used to absorb the heat generated in chain reactions is a coolant.
- In nuclear reactors energy set free is in the form of heat which could be converted into electrical energy.
- The cyclotron can accelerate protons, deutrons, and alpha-particles.
- The property of radiations to ionise the gas through which they pass is used in the Geiger counter.
- The spiral type of accelerator called cyclotron was first developed by Lawrence in 1930.
- carbon -14 provides a radioactive clock for anthropologists. This is called radio carbon dating.
- The curve rises sharply at first and then more gradually until it reaches maximum of 8.8 MeV.
- The average binding energy is 8.5 MeV for moderate nuclei having the mass number range from 40 to 120.
- The binding energy per nucleon = 5.4 MeV.