Help figuring out Electric Potential

In summary: Therefore, the points where the electric potential is 0 are x = ± a/√3.In summary, to find the points where the electric potential is 0 for three point charges laid out in a Cartesian Plane, you can use the equation Vtotal = V1 + V2 + V3 and set it equal to 0. Solving for x, we get x = ± a/√3.
  • #1
Dudemanword
1
0

Homework Statement


Three charges are laid out in a Cartesian Plane:
+q: (0,a)
-q: (0,0)
+q: (0,-a)

There is some point p located on the x-axis in the positive x direction

Show that the points where the Electric potential is 0 is x= +/- a/sqrt(3)

Homework Equations



I believe I am to use
[tex]
\begin{flalign*}
V = \frac{1}{4 \pi \epsilon_0} \ \frac{q}{r}\\
\end{flalign*}
[/tex]
because they are point charges

The Attempt at a Solution


I created right triangles using "P" as a point to start pythagorizing( is that a word?). Eventually I simplified it to q/(x(sqrt(a^2+x^2))
No idea how to get it to +/- a/sqrt(3)
 
Last edited:
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  • #2


I appreciate your attempt at solving this problem. However, I believe there may be some errors in your approach.

Firstly, the electric potential at a point due to a point charge is given by:

\begin{flalign*}
V = \frac{1}{4 \pi \epsilon_0} \frac{q}{r}
\end{flalign*}

where q is the magnitude of the charge, r is the distance from the point charge, and ε0 is the permittivity of free space.

In this case, we have three point charges, so the total electric potential at point P (located on the x-axis) can be found by adding the individual potentials at that point:

\begin{flalign*}
V_{total} = V_1 + V_2 + V_3 = \frac{1}{4 \pi \epsilon_0} \left(\frac{q}{r_1} + \frac{-q}{r_2} + \frac{q}{r_3}\right)
\end{flalign*}

where r1, r2, and r3 are the distances from each charge to point P.

To find the points where the electric potential is 0, we need to set Vtotal equal to 0 and solve for x. This gives us the following equation:

\begin{flalign*}
0 = \frac{1}{4 \pi \epsilon_0} \left(\frac{q}{\sqrt{x^2 + a^2}} - \frac{q}{x} + \frac{q}{\sqrt{x^2 + a^2}}\right)
\end{flalign*}

Simplifying this equation, we get:

\begin{flalign*}
0 = \frac{1}{4 \pi \epsilon_0} \left(\frac{q}{x} + \frac{2q}{\sqrt{x^2 + a^2}}\right)
\end{flalign*}

Multiplying both sides by 4πε0 and then by x, we get:

\begin{flalign*}
0 = q + 2q\sqrt{\frac{a^2}{x^2}+1}
\end{flalign*}

Solving for x, we get:

\begin{flalign*}
x = \pm \frac{a}{\sqrt
 
  • #3


First, let's define some variables:
- q: charge of each point charge
- a: distance between the charges (in the y-direction)
- x: distance between the point p and the origin (in the x-direction)

To find the electric potential at point p, we can use the equation you provided:
V = (1/4πε0) * (q/x)

To find the potential at point p, we need to add the potential contributions from each of the three point charges. Since the potential is a scalar quantity, we can simply add the individual potentials together.

The potential contribution from the first +q charge is:
V1 = (1/4πε0) * (q/(x-a))

The potential contribution from the second -q charge is:
V2 = (1/4πε0) * (-q/x)

The potential contribution from the third +q charge is:
V3 = (1/4πε0) * (q/(x+a))

Now, we can add these three potentials together to get the total potential at point p:
V = V1 + V2 + V3
V = (1/4πε0) * (q/(x-a) - q/x + q/(x+a))

We want to find the value of x where the potential is 0, so we can set V=0 and solve for x:
0 = (1/4πε0) * (q/(x-a) - q/x + q/(x+a))

Multiplying both sides by 4πε0 and simplifying, we get:
0 = q/(x-a) - q/x + q/(x+a)
0 = q(x+a)(x-a) - q(x-a)(x+a) + q(x-a)x
0 = q(x^2+a^2-x^2+a^2) - q(x^2-a^2+x^2-a^2) + q(x^2-ax)
0 = q(2a^2) - q(2a^2) + q(x^2-ax)
0 = q(x^2-ax)
0 = x(x-a)

This gives us two solutions for x:
x = 0 and x = a

However, we know that x cannot be 0 because that would place point p on top of the -q charge. Therefore, the only valid solution for x is x =
 

1. What is electric potential?

Electric potential is the amount of electric potential energy per unit charge at a specific point in an electric field. It is a scalar quantity measured in volts (V).

2. How is electric potential different from electric potential energy?

Electric potential is the potential energy per unit charge, while electric potential energy is the total potential energy of a system of charges. Electric potential is a property of a specific point in an electric field, while electric potential energy is a property of a system of charges.

3. How do I calculate electric potential?

Electric potential can be calculated using the formula V = kQ/r, where V is electric potential, k is the Coulomb's constant, Q is the charge, and r is the distance from the point of interest to the source of the electric field. Alternatively, it can also be calculated using the integral V = -∫E•dr, where E is the electric field and r is the distance traveled along the path of integration.

4. What factors affect electric potential?

The electric potential at a point is affected by the amount and distribution of charge in the electric field, as well as the distance from the source of the electric field. Additionally, the medium in which the charges are located can also affect the electric potential.

5. How is electric potential related to electric potential difference?

Electric potential difference, also known as voltage, is the difference in electric potential between two points in an electric field. It is measured in volts and is calculated by subtracting the electric potential at the initial point from the electric potential at the final point. In other words, it is the change in electric potential between two points.

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