# Moving Charges and Magnetism Problem

1. Aug 16, 2014

### anraphy

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

Two particles A and B having equal charges +6C, after being accelerated through the same potential difference enter a region of uniform magnetic field and describe circular path of radii 2 and 3cm repectively. The ratio of mass of A and B is ______

2. Relevant equations

Force on the particle in a magnetic field = Bqv

In a circular path, mv^2/r = Bqv
→r = mv/Bq

3. The attempt at a solution

I don't know if I should consider their velocities to be equal.
If the velocities are equal, the r(A)/r(B) = 2/3 which is incorrect.

2. Aug 16, 2014

### TSny

Hello, anraphy. Welcome to PF!

Do you know how to relate the final speed of a particle to the potential difference through which it is accelerated?

3. Aug 16, 2014

### anraphy

Potential Difference and Velocity

E = Vq
→0.5mv^2=Vq
→v = √(2Vq/m)
OR
→V=0.5mv^2/q

where
V-potential difference
m-mass of the particle
v-velocity of the particle
E-energy of the particle
q-charge on the particle

4. Aug 16, 2014

### TSny

OK. Good. Can you see how to use that?

5. Aug 16, 2014

### Nero26

Hello, anraphy
The particles have different masses but have equal charge.So when it's accelerated through same potential difference, they will gain equal electric energy=Vq=kinetic energy
Vq=.5m1v12=.5m2v22
∴m1/m2=(v2/v1)2
Similarly when entering in Magnetic field due to different velocities they will follow different circular path of radii ra,rb respectively.
m1v1/ra=m2v2/rb=qB

Last edited: Aug 16, 2014
6. Aug 16, 2014

### anraphy

I think I got it. Thank You :)

7. Aug 17, 2014