In a cyclotron, a charged particle

Options

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

Answer

To solve the question regarding the behavior of a charged particle in a cyclotron, we can break down the process step by step.

### Step-by-Step Solution:

1. **Understanding the Cyclotron**: A cyclotron is a type of particle accelerator that uses a combination of electric and magnetic fields to accelerate charged particles, such as protons or electrons, to high speeds.

2. **Components of the Cyclotron**: The cyclotron consists of two D-shaped electrodes (called "dees") placed in a magnetic field. The magnetic field is perpendicular to the plane of the dees.

3. **Acceleration in the Electric Field**: When a charged particle enters one of the dees, it is subjected to an electric field that exists between the dees. This electric field accelerates the particle, increasing its kinetic energy and speed.

4. **Circular Motion in the Magnetic Field**: Once the particle exits the dee and enters the magnetic field, it experiences a magnetic force that causes it to move in a circular path. The magnetic force acts as a centripetal force, keeping the particle in circular motion.

5. **Frequency of Rotation**: The frequency of the particle's rotation is determined by the strength of the magnetic field and the charge-to-mass ratio of the particle. As the particle gains speed, it moves to a larger radius within the cyclotron.

6. **Repetition of the Cycle**: The particle continuously moves back and forth between the dees, getting accelerated each time it passes through the electric field. This process repeats, allowing the particle to gain energy and speed with each cycle.

7. **Conclusion**: The correct statement regarding the behavior of the charged particle in a cyclotron is that it speeds up while it is in the electric field between the dees and moves with constant velocity while in the magnetic field. Therefore, the particle undergoes acceleration only when it is in the electric field, not while it is in the magnetic field.

### Final Answer:
The charged particle in a cyclotron speeds up between the dees due to the electric field and moves with constant velocity while in the magnetic field.

---