RadioActivity And Nuclear Reactions


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       The process of nuclear fission can be understood on the basis of liquid drop model proposed by Yakov Frenkel, Neils Bohr and John Wheeler. In this model, nucleus of U-235 is treated as a positively charged, non-compressible drop of a liquid which is enclosed by a thin elastic membrane. When the nucleus is in stable state, it is spherical in shape. Inside this nucleus two types of forces are operating. These forces are called electrostatic force and nuclear force. The electrostatic force is the force which is exerted by one charge particle on other charged particle. As we know that positively charged protons are present in the nucleus, so every proton present in the nucleus tends to repel other protons due to electrostatic force of repulsion. But the electrostatic force of repulsion is balanced by nuclear force of attraction between the constituents of the nucleus.

Now, when a slow moving neutron hits the nucleus of U-235, it disturbs the balance of forces in the nucleus. Due to collision of neutron with nucleus of U-235 the magnitude of electrostatic force of repulsion increases which results in breaking the nucleus into small fragments with emission of a large amount of energy.

Liquid Drop Model Of Nuclear Fission

Test Your Understanding and Answer These Questions:

  1. Who proposed liquid drop model of nuclear fission?

  2. What is nuclear theory?

  3. What is definition of electrostatic force?

  4. What is definition of nuclear force?