Electric Potential Question. Involves eV (electron volt).?

Question

The question goes like this:
Point A is at a potential of +210 V, and point B is at a potential of -140 V. An α-particle is a helium nucleus that contains two protons and two neutrons; the neutrons are electrically neutral. An α-particle starts from rest at A and accelerates toward B. When the α-particle arrives at B, what kinetic energy (in electron volts) does it have?

I think this has to do with the concept of Total Energy, but could someone explain how I would apply it to find kinetic energy in terms of electron volts? Do I just find the work that was done and then convert it to electron volts?

Avinash · Accepted Answer

Charge on alpha particle Q = +2e (where +e = charge on a proton)
Change in potential energy = 2e*(-140 V - 210 V) = 2e(-350 V) = -700 V * e = -700 eV
By conservation of energy,
change in kinetic energy = - change in potential energy = -(-700 eV) = 700 eV
Kinetic energy at A = 0 (because alpha particle is at rest at A)
Therefore kinetic energy at B = 700 eV

Ans: 700 eV

bragadog · Answer

The work done is the product of the charge by the potential. This is the kinetic energy at B (a well known theorem).
Its value is 2 x 350 =700 eV

? · Answer

electric potential is another way of saying 'voltage' It is the difference in voltage between two points.

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Electric Potential Question. Involves eV (electron volt).?

3 Answers