# Magnetic field affecting an alpha and a beta particle.

1. Apr 20, 2012

### gabloammar

1. The problem statement, all variables and given/known data
An $\alpha$-particle and a β-particle are both travelling along the same path at a speed of 1.5x106 ms-1.

They then enter a region of uniform magnetic field. The field is a square with sides of 1 cm.

The magnetic field is normal to the path of the particles and is into the plane of the paper.

Calculate the ratio 'radius of the path of the alpha particle/radius of the path of the beta particle.'

2. The attempt at a solution

I don't even know how to start thinking about this question. I mean I know that the radius of the alpha particle will be greater than that of the beta particle because of their differences in mass and charge but how do you do go about that in fractions?

2. Apr 20, 2012

### JameB

Hint: What are the relevant equations and how would they differ for α/β particles?

3. Apr 21, 2012

### gabloammar

r = mv/BQ? no?

For an α-particle, m would be (1840x4) times greater than for a β-particle [because it's a helium nucleus and a β-particle is an electron]. v is the same for both particles. B is also the same. Q, the charge, on the other hand, will be positive and negative for alpha and beta respectively, with values [if they're needed in the first place] of +4e and -e for alpha and beta respectively. I hope I'm right with all that data.

Here's what's bothering me. What do I do with this to answer the question? I mean how do I use it?