Electric Potential Difference homework

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Homework Help Overview

The problem involves calculating the kinetic energy of an alpha-particle as it moves between two points with different electric potentials, specifically from point A at +220 V to point B at -120 V. The context is within the subject area of electric potential difference and energy conversion in electrostatics.

Discussion Character

  • Exploratory, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the relationship between electric potential difference and kinetic energy, referencing the equation KE=q(VA-VB). There is an exploration of the charge of the alpha particle and its implications for the calculation. Questions arise regarding the correct values to use for charge and potential differences.

Discussion Status

Some participants have provided guidance on the equation and the values for charge and potentials. There is an ongoing clarification of the variables involved, particularly concerning the charge of the alpha particle and the calculation of the potential difference.

Contextual Notes

Participants are navigating the conversion between units of volts and electron volts, with some uncertainty about the necessity of converting charge to Coulombs for the calculation. The original poster expresses confusion about their calculations and seeks further assistance.

spoonthrower
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Point A is at a potential of +220 V, and point B is at a potential of -120 V. An alpha-particle is a helium nucleus that contains two protons and two neutrons; the neutrons are electrically neutral. An alpha-particle starts from rest at A and accelerates toward B. When the alpha-particle arrives at B, what kinetic energy (in electron volts) does it have? Plz help. thanks.

Here are my thoughts so far... i know the mass of the alpha particle is 4 amu. The charge of the alpha particle is 2e. 6.25*10^18=1e so the charge of the alpha particle is 3.2*10^-19 C. I think i should use the following equation to solve this problem: KE=q(VA-VB). this will give me the answer in volts, however i need eV so 1V=1eV/(1.6*10^-19 C) When i plug in these numbers i am not getting the right answer. please let me know what i am doing wrong. thanks.
 
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Since you want the answer in eV, no point in converting charge to Coulombs (and back). Your equation is correct: KE=q(VA-VB). What's q? What's Va-Vb?
 
would q be equal to 2 since their are 2 e's in an alpha particle? And VA=220 and VB=-120 so KE=2(220-120)? thanks.
 
Almost.

q = 2e. Va = 220V; Vb = -120V; so, Va-Vb = (220V) - (-120V).
 

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