How Does Charge Affect Kinetic Energy in Particle Accelerators?

[Physicsist]

I've taken a screen shot of the question
[PLAIN]http://img803.imageshack.us/img803/753/73615252.png
I know the answer (I've given it in the spoiler below), I don't understand why that is the answer

Spoiler

answer: kinetic energy

Thanks if you can help :)

 

[vanhees71]

With "potential difference", one refers to electric potential difference. A charged particle, accelerated by the corresponding electric field, gains kinetic energy

$$\Delta E_{\text{kin}}=q U,$$

where $U$ is the potential difference, and $q$ is the charge of the particle. Now you only have to figure out what's the charge of a proton and that of am $\alpha$ particle.

 

[Physicsist]

I see, thanks!

Having thought about that, I've learned it this way:
Combining electrical field strength, E_fs = Voltage / distance
and E_fs = Force / charge

Force . distance = Voltage . charge
Work done by the particle accelerator = Voltage . charge
The work done by the accelerator is converted into kinetic energy,
Kinetic energy = Voltage . charge
The voltage is constant, 500k. The charge of the proton is positive (one unit, whatever the charge of a proton is) and the charge of an alpha particle is positive (two units, whatever the charge of a proton is) as it has two protons [the neutrons have no charge].

So, twice the charge means twice the kinetic energy! I must be right.
I'm happy with that now, thanks again :)