Electric Potential Due to point charges

In summary: So in part (b) you are bringing a charge from infinity to the point (0, 0.6m). The potential at that point is given by the result of part (a). The potential at infinity is zero. So the difference in potential energy is qV = (-3.00 μC)(53940 Volts) = -162,820 μJ. You should express that in SI units.
  • #1
MidgetDwarf
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Homework Statement



  1. Two particles each with a charge of +3.00 μC are located on the x axis, with one particle at x = -0.80 m, and the other particle at x = +0.80 m.
    1. a) Determine the electric potential on the y-axis at the point y = 0.60 m.
    2. b) What is the change in electric potential energy of the system if a third particle of charge

      q = - 3.00 μC is brought from infinity to the point on the y-axis where y = 0.60 m?

Homework Equations



Vp=KQ/r
Vb-Va
Pythagoras Theorem

The Attempt at a Solution



First I draw the diagram. I place one charge at x=-0.80m and the second at x=0.80m. The point at which I want to calculate the potential energy is at (0,0.60m). I apply the Theorem of Pythagoras to get the radial distance from where the point charge is located to the point I want to find potential.

r=Sqrt(x^2 +y^2)
r=1m

Since I have two charges, the Total potential is equal to the sum of both of the charges.
Vtotal= V1 +V2.
Since Both charges are equal and are the same distance apart to the point p,
Vtotal=53940 V.

This is my answer for part A.

for part B, I want to find the potential difference Vb-Va. A charge comes into point P from infinity, So we say that at infinity it has zero potential. However, at P, the potential is -44950 V.

Now, my problem is. Can I use my result from part a to answer part b. Meaning Va=53940 V.
Since the charges are not moving from P (the ones that moved from the x-axis).

Would my answer be Vb-Va=-44950-53940
Vb-Va=-98,890?

Sorry for this beginner problem. I am not sure if I am understanding the concept of Potential due to Point Charges.
 
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  • #2
Part (a) looks good. You might want to express the result to the same number of significant figures as the given data.

For part (b) you need to know the difference between electric potential (Volts) and electric potential energy (Joules). Electric potential energy is associated with the work that needs to be done to assemble a system, bringing in the pieces from infinity where the potential is zero.

You can use the result of part (a) in that the potential energy of a an object with charge q brought to a location where the electric potential is V is given by qV. It's helpful to remember that the Volt is a unit that is made up of other units (a compound unit) namely Volt = Joules/Coulomb, or energy per charge quantity.
 

1. What is electric potential due to point charges?

Electric potential due to point charges is a measure of the potential energy that a charge would have at a specific point in an electric field. It is caused by the interaction between the charge and the electric field, and is measured in volts (V).

2. How is electric potential due to point charges calculated?

The electric potential due to point charges can be calculated using the formula V = kQ/r, where V is the electric potential, k is the Coulomb's constant, Q is the charge of the point charge, and r is the distance from the point charge.

3. Does the magnitude of the point charge affect the electric potential?

Yes, the magnitude of the point charge does affect the electric potential. As the magnitude of the point charge increases, the electric potential also increases. This is because the charge has a stronger influence on the electric field at that point.

4. How does the distance from the point charge affect the electric potential?

The distance from the point charge affects the electric potential in an inverse relationship. As the distance increases, the electric potential decreases. This is because the electric field weakens with distance, resulting in a lower electric potential at further distances.

5. Can multiple point charges affect the electric potential at a single point?

Yes, the electric potential at a single point can be affected by multiple point charges. The effect of each point charge is calculated separately and then added together to find the total electric potential at that point.

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