# Point charges arranged as a trianngle

• jenzao
In summary, the conversation is about finding the x- and y- components of the electric force acting on qC, given three charges at the vertices of an equilateral triangle. The person is having trouble with their calculation and is seeking help. The correct solution involves using the equation F = kqAqC/r^2 and multiplying by the sine of 60 degrees.
jenzao

## Homework Statement

Consider three charges at the vertices of an equilateral triangle of side a = 7 cm. qA = +2 µC, qB = +2 µC, and qC = -1 µC. (see attached picture)

Find the x- and y- components of the electric force acting on qC

## Homework Equations

i am doing everything right, but getting wrong answer ?

## The Attempt at a Solution

x-comp cancel obviously, so I am left with finding y-comp...

F = kqAqC/r^2
= 2.571e-1

sin60(2.571e-1) = 2.2266e-1
multiply by 2 = 4.453e-1 N (this is wrong though)

i can't see the prob. The forces both point in positive y direction, so the y vectors sum

#### Attachments

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jenzao said:

## The Attempt at a Solution

x-comp cancel obviously, so I am left with finding y-comp...

F = kqAqC/r^2
= 2.571e-1

sin60(2.571e-1) = 2.2266e-1
multiply by 2 = 4.453e-1 N (this is wrong though)
=k.qA.qC/r^2
=9E9 x 2E-6 x 1E-6/0.07^2
=3.67

I see you are dividing by 7
Two mistakes it's 7cm and then its r^2

I would first commend the student on their attempt to solve the problem and their use of the correct equations. However, it is important to double-check calculations and make sure all units are consistent.

In this case, it seems like there may be a mistake in the calculation of the electric force. It is important to remember that the electric force is a vector quantity and has both magnitude and direction. The direction of the force acting on qC will depend on the relative positions of the charges and the direction of the electric field they create.

I would suggest reviewing the calculation and making sure the direction of the force is taken into account. It may also be helpful to draw a vector diagram to visualize the forces acting on qC. Additionally, checking the units and making sure they are consistent can help identify any errors.

If the issue persists, it may be helpful to seek assistance from a classmate or the instructor for further clarification. As a scientist, it is important to approach problems with a critical mindset, double-checking calculations and seeking clarification when needed.

## 1. What is the electric potential at the center of a triangle formed by three point charges?

The electric potential at the center of a triangle formed by three point charges can be calculated by summing the electric potential contributions from each individual charge using the equation V = kQ/r, where k is the Coulomb's constant, Q is the charge of each point charge, and r is the distance from the center to each charge.

## 2. How does the electric field vary at different points within and outside of the triangle?

The electric field within the triangle will vary depending on the relative positions and magnitudes of the point charges. At points outside of the triangle, the electric field will decrease as the distance from the center of the triangle increases. The direction of the electric field will also be dependent on the charges' positions and magnitudes.

## 3. What is the net force on a test charge placed at the center of the triangle?

The net force on a test charge placed at the center of the triangle will be zero, as the electric forces from each point charge will cancel out due to the symmetry of the triangle. This is known as the principle of superposition.

## 4. Can the arrangement of the point charges in a triangle create a stable equilibrium point?

Yes, it is possible for the point charges to be arranged in a way that creates a stable equilibrium point at the center of the triangle. This would require the charges to have equal magnitudes and be placed at equal distances from the center of the triangle.

## 5. How does the potential energy of the system change when the charges are moved?

The potential energy of the system will change depending on the movement of the charges. When the charges are moved closer together, the potential energy will decrease, and when they are moved farther apart, the potential energy will increase. This is because the potential energy is directly proportional to the distance between the charges.

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