CBSE Class 12-science Answered

There are 2 semicircular discs where the motion of the charged particle takes place. these are called dees.The front section is open for free movements of particles one to another dees.The whole system is made evacuated to avoid collisions between the ions and air molecules.When high frequency voltage is applied to these Dees the +ve charged particle released at the centre (1).They move in the semicircular path in one dees and arrive in the gap between the Dees in T/2, here T is the period of revolution. From equation (i) we get the cyclotron frequency f_c.The frequency of the applies voltage is f_a is adjusted in the manner that the p[polarity of the dees is reversed in the same time that it takes the ions to complete one half of the revolution. so,

f_c =f_a

The operation of the cyclotron is based on the fact that the time for 1 revolution of the ion is independent of the speed or radius.

Uses

Cyclotron is used to bombard nuclei with energetic particles and observe the nuclear reactions.

It is used to implant ions into solids and modify their properties or synthesis of new material. 

It is used for different radioactive tests in hospitals for diagnosis.

Limitations

• At high speed relativistic effects must be encounter, the mass of the ion is no longer constant and delicate resonance condition f_c =f_a does not true.

• Electron required high frequency.

• Maintaining the uniformity of the magnetic field over the extended region of the dees can also be a problem.