# Magnetic Field and acceleration relationship I just need to understand the relationship between a magnetic field and a charged particle. Can i say that a magnetic field cannot accelerate a moving charge particle since it cannot change the speed of the particle, however I think it can change the velocity of the particle? Am i wrong ?

My second question is , could a positively charged particle have an constant acceleration produced by a uniform electric field or is there another influence acting on it?

## 1 Answer

You are correct that a charged particle moving in a magnetic field will experience a force such that the direction of its velocity changes but not its speed. This still constitutes acceleration since acceleration is the rate of change of velocity and changing direction of motion means changing velocity.

A positively charged particle in a uniform electric field will experience a constant electric force in the direction of the field. Assuming there are no other forces acting on it it will accelerate in that directions.

• alright so that's the only flaw with that statement right? that the speed doesn't change. And that's my question are there another forces? How can we know. I'll add an image of the graph of velocity vs time – Andrew Mar 29 '17 at 2:42
• The force on a charged particle moving perpendicularly through a magnetic field is F=qvB. F causes v to change direction, which in turn causes F to change direction, which makes the particle go in a circle at a steady speed. The acceleration for uniform circular motion is a=v^2 / r. – Paul B Mar 29 '17 at 18:49