An ion moves in a circle in a uniform magnetic field. Which single change would increase theradius of the circular path?

The radius of the circular path of an ion moving in a uniform magnetic field can be increased by making one of the following changes:

1. Increasing the speed of the ion: The radius of the circular path is directly proportional to the speed of the ion. Therefore, if the speed of the ion increases, the radius of the circular path will also increase.

2. Increasing the mass of the ion: The radius of the circular path is also directly proportional to the mass of the ion. Therefore, if the mass of the ion increases, the radius of the circular path will also increase.

3. Decreasing the strength of the magnetic field: The radius of the circular path is inversely proportional to the strength of the magnetic field. Therefore, if the strength of the magnetic field decreases, the radius of the circular path will increase.

Remember, only one of these changes would need to occur to increase the radius of the circular path.