Question

In a cyclotron, a charged particle

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

Hint:

The magnetic force only turns the particle, and the electric field in the gap speeds it up, so it is always accelerating.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept
Inside a dee there is no electric field. The magnetic force \(q\vec{v}\times\vec{B}\) is perpendicular to the velocity, so the speed stays the same but the direction changes.

Step 2: Calculation
A change in direction means a centripetal acceleration. In the gap between the dees the alternating electric field increases the speed.

Step 3: Compare the options
So the particle is accelerated at all times. The magnetic field never changes the speed, and the particle does not speed up in the dee or slow down there.

Final Answer:
The particle undergoes acceleration all the time. \[ \boxed{\text{(A) }\text{undergoes acceleration all the time}} \]