# Magnetic Fields and Forces

1. Homework Statement
Prove that the time for one revolution of a charged particle moving perpendicular to a uniform magnetic field is independent of it's speed. Write an expression that gives the period T in terms of the mass and charge of the particle and the magnetic field strength.

2. Homework Equations

Fc=4*pi*^2mr/T^2

Fm=qvB

3. The Attempt at a Solution

Fc=Fm

v=4*pi*^2mr/T^2qB

is that right?

Related Introductory Physics Homework Help News on Phys.org
alphysicist
Homework Helper
Hi soul5,

You're expressions look like they are true, but they don't answer the question. The question asks for the expression for the period, but that expresion is not supposed to have r and v in it.

If you can find a formula for the period in terms of r and v you can use that to eliminate r and v in your equation.

So let's say you have an object moving at speed v in a circular path of radius r. What is the period (time to go once around the circle)? Once you have that, use it to eliminate r and v. What do you get?