Electric Potential Energy of Three Point Charges

In summary, the problem involves finding the electric potential energy of three point charges placed at the vertices of an equilateral triangle with sides of length 0.550m. Using the equation U = kQ1Q2/r, the potential energy between the three points is calculated by summing the potential energy between each pair of points. However, the answer obtained is incorrect due to a mistake in the given charge value, which was supposed to be in microCoulombs instead of nanoCoulombs. Once this mistake is corrected, the correct answer of 9.56E-8 J is obtained.
  • #1
lwelch70
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0

Homework Statement



Three equal point charges, each with charge 1.95 nanoC , are placed at the vertices of an equilateral triangle whose sides are of length 0.550m . What is the electric potential energy of the system? (Take as zero the potential energy of the three charges when they are infinitely far apart.)
Use = 8.85×10−12 for the permittivity of free space.

Homework Equations



U = kQ1Q2/r

The Attempt at a Solution



So I know how to go about solving the problem. I take the potential energy between points 1 and 2, 1 and 3, and then 2 and 3 and sum them together.

OR since it is equilateral and all the same charge and I skip a little.

U=3KeQ2/r right?

When I do these steps I come to a final answer of 9.56E-8 J but know that this is not right, first because Mastering Physics told me I was wrong, second because I know that it cannot approach zero unless the distance is approaching infinity. Any suggestions on where I am going wrong?
 
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  • #2
Oh wow. Haha. Okay guys I figured it out. It wasn't nano Coulomb it was micro. Got the answer on the last try.
 

1. What is electric potential energy?

Electric potential energy is the energy that a charged object has due to its position in an electric field. It represents the ability of the charged object to do work on other charged objects.

2. How is electric potential energy calculated?

The electric potential energy of a system is calculated by multiplying the charge of the object by the electric potential at its position. The electric potential is determined by the electric potential due to each of the individual charges in the system.

3. What is the formula for calculating the electric potential energy of three point charges?

The formula for calculating the electric potential energy of three point charges is U = k(q1q2/r12 + q1q3/r13 + q2q3/r23), where U is the electric potential energy, k is the Coulomb's constant, q1, q2, and q3 are the charges of the three point charges, and r12, r13, and r23 are the distances between the charges.

4. How does the electric potential energy change when the distance between two charges is increased?

When the distance between two charges is increased, the electric potential energy decreases. This is because the electric force between the two charges decreases as the distance between them increases, resulting in a decrease in the potential energy.

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

The electric potential energy is directly proportional to the electric potential. This means that as the electric potential increases, the electric potential energy also increases. Additionally, the electric potential is the change in electric potential energy per unit charge, so it represents how the electric potential energy is distributed in a system.

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