What is the electric potentional for these charges?

In summary, the problem involves finding the electric potential energy for a given array of charges: q1 = +4.0 µC, q2 = +3.0 µC, and q3 = −1.0 µC. Using the equation U=kq1q2/r12, U=kq1q3/r13, and U=kq2q3/r23, the distances between each charge can be calculated using the Pythagorean theorem. The final potential energy, when all three values are added together, is 0.59 millijoules. However, it is important to take into account the positive and negative charges when calculating the distances between them.
  • #1
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Homework Statement



Find the electric potential energy for the following array of charges: charge q1 = +4.0 µC is located at (x, y) = (0.0, 0.0) m; charge q2 = +3.0 µC is located at (4.0, 3.0) m; and charge q3 = −1.0 µC is located at (0.0, 3.0) m.

_____ mJ

Homework Equations



U=kq1q2/r12
U=kq1q3/r13
U=kq2q3/r23

The Attempt at a Solution



Obviously, I just plug in the charges and the k constant, 8.99 x10^9, but I don't know what to put in for r. Do I have to calculate x and y components and add them up?
 
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  • #2
well i hope you know that each charge constrabute to potential. so say there are 1,2,3 charges. if you want to calcualte the potential due to charge 1,2 on 3 just do 1 on 3 and 2 on 3. then add them up.

BA
 
  • #3
see "relevant equations". I already know I have to add them all up. I just don't know how to calculate r.
 
  • #4
oh my mistake.

so we know x2 + y2=r2 <---Pythagorean theorem

from this and the corrdinate you are given you can find r
 
  • #5
I tried that, but it says it's wrong.

Using it, r12 would be: sqrt. (4^2 + 3^2) = 5

r13: sqrt. (0^2 + 3^2) = 3

r23: sqrt. (3^2 + 0^2) = 0

and plugging it into the equation kq1q2/r12, kq1q3/r13, kq2q3/r23 and adding them all up gives me 5.9 x 10^-4 Joules, which is 0.59 millijoules, which it says is wrong.

Can you please help me? I don't know what I'm doing wrong.
 
  • #6
Ammora said:
I tried that, but it says it's wrong.

Using it, r12 would be: sqrt. (4^2 + 3^2) = 5

r13: sqrt. (0^2 + 3^2) = 3

r23: sqrt. (3^2 + 0^2) = 0<---- this is wrong, it should be 3

and plugging it into the equation kq1q2/r12, kq1q3/r13, kq2q3/r23 and adding them all up gives me 5.9 x 10^-4 Joules, which is 0.59 millijoules, which it says is wrong.

Can you please help me? I don't know what I'm doing wrong.

btw can you post the original question. and is this from mastering physics?
...so are we trying to find the electric potential of q1 due to q2 and q3?.. because I am kinda confussed by the wording
 
  • #7
Find the electric potential energy for the following array of charges: charge q1 = +4.0 µC is located at (x, y) = (0.0, 0.0) m; charge q2 = +3.0 µC is located at (4.0, 3.0) m; and charge q3 = −1.0 µC is located at (0.0, 3.0) m.

We have to find the electric potential for all 3 charges.
 
  • #8
No, it's from Webassign, not a book.
 
  • #9
first take the + and - into account
next say distance btw q1 and q2 take the differnece btw the point then use that to find distance...

oh mastering physics is like Webassign..

i used Webassign for math
 

1. What is electric potential?

Electric potential is a measure of the potential energy per unit charge at a certain point in an electric field.

2. How is electric potential different from electric field?

Electric field is a measure of the force per unit charge at a certain point in an electric field, while electric potential is a measure of the potential energy per unit charge.

3. How is electric potential calculated?

Electric potential is calculated by dividing the work done in moving a unit positive charge from infinity to that point by the magnitude of the charge.

4. How does the distance between charges affect electric potential?

The electric potential between charges decreases as the distance between them increases. This can be seen in the inverse relationship between electric potential and distance in the formula V= kQ/r, where k is a constant, Q is the charge, and r is the distance between the charges.

5. Can electric potential be negative?

Yes, electric potential can be negative. This indicates that the potential energy of a charge at that point is lower than the potential energy at infinity, and the charge would experience an attractive force towards that point.

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