Uniform circular motion in a magnetic field

[umdnjmed]

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Can someone please confirm if my understanding of this concept is right;

When the radius of an orbiting charge in a magnetic field is decreased, the magnetic force acting on the charge increases. When the radius increases, the magnetic force acting on it decreases. However, even though the force changes in both instances, the velocity remains constant.

 

[umdnjmed]

Also, does this mean that for a given charge, the velocity in orbit will always be the same, regardless of the magnetic force and radius? In other words, in order to change the velocity, you would have to change the magnitude of the charge. Is this correct?

 

[hiaips]

Can someone please confirm if my understanding of this concept is right;

When the radius of an orbiting charge in a magnetic field is decreased, the magnetic force acting on the charge increases. When the radius increases, the magnetic force acting on it decreases. However, even though the force changes in both instances, the velocity remains constant.

The velocity cannot remain constant if there is a net force acting on the object. Maybe what you meant was "speed". Since the magnetic force always acts perpendicular to the direction of motion, it does no work on the particle in question. Hence, the particle's speed must remain the same.

As far as your other question:
q v B = m v^2 / R
B = m v / (R * q)

Hence, B does decrease with increasing radius (and vice versa).

 

[umdnjmed]

i did mean speed. thanks for the clarification and explanation.