# Kinetic energy in volts

1. Jan 22, 2008

### rcmango

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

Point A is at a potential of +240 V, and point B is at a potential of -120 V. An -particle is a helium nucleus that contains two protons and two neutrons;

the neutrons are electrically neutral. An -particle starts from rest at A and accelerates toward B.

When the -particle arrives at B, what kinetic energy (in electron volts) does it have?
in eV

2. Relevant equations

3. The attempt at a solution

W = q * (chng in V)

q is the charge stored by a dialectric capacitor.

and change in V is the electric potential difference.

chng in V = Vb - Va = -360 V correct?

so where does the q come from?

2. Jan 22, 2008

### chroot

Staff Emeritus
Let me give you the definition of an "electron volt:"

The energy gained by an electron, in moving through a potential of one volt, is one electron volt.

- Warren

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