Electric Potential Energy: Work Required to Move 3 Charges Out to Infinity

In summary, the problem is asking for the amount of work needed to move three charges infinitely far from each other, and the formula used is W = -kq_{1} [(q_{2}/r_{12}) + (q_{3}/r_{13})]. After finding the work for each individual charge, it is realized that only two charges need to be moved to infinity and the first charge can be forgotten.
  • #1
ayreia
6
0

Homework Statement



Three charges are distributed as follows:

http://tinypic.com/r/1fviq0/5

How much work must an external force do to move them infinitely far from each other?

Homework Equations



W = -[itex]\Delta[/itex]U = (kq[itex]_{1}[/itex]q[itex]_{2}[/itex])/r

The Attempt at a Solution



So what I did was find the work needed to move each individual charge out to infinity using

W = -kq[itex]_{1}[/itex] [(q[itex]_{2}[/itex]/r[itex]_{12}[/itex]) + (q[itex]_{3}[/itex]/r[itex]_{13}[/itex])].

For q[itex]_{1}[/itex] this gave me -0.539 J, q[itex]_{2}[/itex] +0.862 J, and q[itex]_{3}[/itex] -0.861 J. I thought I could just add them together to get the total work, but this is incorrect. I'm completely stumped now as to how to proceed. Can someone point me in the right direction? Thanks a lot!
 
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  • #2
hi ayreia! :smile:

you only need to move two of them to infinity, don't you? :wink:

(also, once you've moved the first one, you can forget about it when you move the second one)
 
  • #3
Oh, right! That makes sense, thanks a lot! :D
 

FAQ: Electric Potential Energy: Work Required to Move 3 Charges Out to Infinity

1. What is electric potential energy?

Electric potential energy is the amount of work required to move a charged particle from one point to another in an electric field.

2. How is electric potential energy related to work?

Electric potential energy is directly related to work, as it is the amount of work required to move a charged particle against the electric field.

3. What is the significance of moving 3 charges out to infinity in relation to electric potential energy?

Moving 3 charges out to infinity allows us to calculate the total electric potential energy of the system, as the potential energy at infinity is considered to be zero.

4. How is the work required to move 3 charges out to infinity calculated?

The work required to move 3 charges out to infinity is calculated by taking the product of the charge of each particle, the initial and final distances from the center of the system, and the electric field strength at those distances.

5. What is the difference between electric potential and electric potential energy?

Electric potential is the electric potential energy per unit charge at a particular point, while electric potential energy is the total amount of energy required to move a charge from one point to another.

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