In a cyclotron, a charged particle

Options

A. undergoes acceleration all the time.
B. speeds up between the dees because of the magnetic field.
C. speeds up in a dee.
D. slow down within a dee and speeds up between dees.

Answer

a

Explanation

In a cyclotron, a charged particle undergoes circular motion under the effect of magnetic field and increases its speed under the effect of electric field.
The charged particle describes a circular path inside a dee and is accelerated by electric field between the dees. Inside a dee, electric field is zero, so the particle will experience only the magnetic force. As a result, after following a semi-circular path it will come into the gap between the dees. Simultaneously, the polarity of electric field will change and thus, the charged particle is accelerated and enters another dee following the circular path of a larger radius. Now we can say that all the time, the particle is accelerating either due to electric field or due to magnetic field.
Hence, option (a) is correct.