# TWO Point Charges on the x-axis and an electric field graph

• danielcheung1
In summary, the conversation discusses two point charges, qA and qB, located at positions x=a and x=b on the x-axis. The graph shown is of the x-component of the electric field, and the question is asking about the signs of the charges. The individual discussing the problem suggests that since the graph is symmetrical, the charges should be the same sign. However, they are unsure how to interpret the graph and the electric field lines. Another individual suggests that the graph may indicate the strength of the electric field and that the charges are likely of opposite signs since the field is not zero between a and b. They also mention that the graph being symmetrical does not determine which charge, a or b, is positive or negative
danielcheung1

## Homework Statement

Two point charges qA and qB are located on the x-axis at x=a and x=b. The figure is a graph of Ex, the x-component of the electric field.
What are the signs of qA and qB?

## Homework Equations

http://session.masteringphysics.com/problemAsset/1071455/4/29.EX31.jpg

## The Attempt at a Solution

I feel like... since the graph is symmetrical, the two charges should be the same sign, eg, either both negative or both positive, but i do not know how to interpret the electric field graph! I don't understand how the electric field lines tell me anything, they are going neither towards or away from the point charges... I'm trying to think if the asymptotes mean anything but I just don't know where to begin?

if both charges were same .. field should have been 0 in between a and b ... which is not .. so i think that they are of opposite sign

so are you saying that the electric field graph as shown in the figure is indicative of electric field strength? I still don't understand what the graph is indicating, what those lines stand for?
and if they were of opposite sign, and the graph is symmetrical, how would i go about deciding which charge, a or b, is positive or negative?

## 1. What is the equation for the electric field created by two point charges on the x-axis?

The electric field created by two point charges on the x-axis is given by the equation E = kQ/(x^2) where k is the Coulomb's constant, Q is the magnitude of the charge, and x is the distance from the point charge to the point where the electric field is being measured.

## 2. How does the distance between the two point charges affect the electric field graph?

The distance between the two point charges affects the electric field graph by causing it to become weaker as the distance increases. This is because the electric field follows the inverse square law, where the strength of the field decreases as the distance increases.

## 3. What is the direction of the electric field created by two point charges on the x-axis?

The direction of the electric field created by two point charges on the x-axis is dependent on the signs of the charges. If the charges are of the same sign, the electric field will be repulsive and point away from the charges. If the charges are of opposite signs, the electric field will be attractive and point towards the charges.

## 4. How does the magnitude of the charges affect the electric field graph?

The magnitude of the charges affects the electric field graph by increasing the strength of the field. The larger the magnitude of the charges, the stronger the electric field will be at any given point. This is because the electric field is directly proportional to the magnitude of the charges.

## 5. Can the electric field graph created by two point charges on the x-axis ever be zero?

Yes, the electric field graph created by two point charges on the x-axis can be zero at certain points between the two charges. This is known as the neutral point, where the electric fields of the two charges cancel each other out and result in a net electric field of zero.

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