# Magnetic Forces and Magnetic Field

1. Oct 24, 2009

### aesura

1. The problem statement, all variables and given/known data

A charged particle with a charge-to-mass ratio of |q| / m = 5.7x10^8 C/Kg travels on a circular path that is perpendicular to a magnetic field whose magnitude is 0.72 T.

How much time does it take for the particle to complete one revolution?

2. Relevant equations

3. The attempt at a solution

:( :(

2. Oct 24, 2009

### aesura

*bump*

i tried to work it tho...not like Im just posting a new thread HEY GUYS COULD U PLEASE DO THIS FOR ME??

the trouble im having is that I can't link t with all my magnetic formulas.... and I've never heard of charge mass ratio...

i tried to work out hte velocity but... not enough data for it...

anyway physicists we need you!!!

3. Oct 24, 2009

### Suy

Fm=qvB
Fc=(mv2)/r
because the particle is moving on a circular path,
so Fm=Fc
rearrange the formula to q/m=?, then solve for the radius
then use the radius to find the circumference,
d/t=v
where d is the circumference
Hope that helps

Last edited: Oct 24, 2009
4. Oct 24, 2009

### aesura

hmmm yea :( indeed... damn it... sorry im med student not a physicist...

that was easy... :*( :*(

F = q v b sin 90
F = qvb

F = mv^2 / r ... obviously since a = v^2/r since it is a centri. force...

qvb = mv^2/r
q/m = v^2/rB
5.7x10^8 C/Kg = v/rB since v must be 2pi.... :(

5.7x10^8 C/Kg x r = 2pi/0.72T

r = 1.53 x10^8 s

thank you so much... this is the correct answer... thanx heaps :)