# Point charges and force of repulsion

• kbyws37
In summary, the equation for the repulsive force between two point charges is Coulomb's law of F = ((k)(q1)(q2))/(r^2), where F scales as 1/r^2. If the separation between the charges is reduced to 0.280 times its original value, the magnitude of the force of repulsion between them would be 12.8 F, which is larger than the original force due to the inverse scaling relationship.
kbyws37
Two point charges are separated by a distance r and repel each other with a force F. If their separation is reduced to 0.280 times the original value, what is the magnitude of the force of repulsion between them?

I don't really understand this question and don't know where to start.
E = ((k)(Q)/r^2

what follows next?

What is the equation for the repulsive force between two point charges, and how does it scale with r?

JeffKoch said:
What is the equation for the repulsive force between two point charges, and how does it scale with r?

It would be Coulomb's law of

F = ((k)(q1)(q2))/(r^2)

So it would be -0.280 times the original r value?

The final answer is 12.8 F but I still don't understand.

Where do you get the minus sign?

O.K., you know that F scales as 1/r^2. When r gets smaller, F must get larger. When r is half it's original value, how much larger does F get?

## 1. What is a point charge?

A point charge is an electric charge that is concentrated at a single point and has no physical size or volume. It is considered a theoretical concept used in physics to simplify calculations and understand the behavior of electric charges.

## 2. How is the force of repulsion between two point charges calculated?

The force of repulsion between two point charges is calculated using Coulomb's Law, which states that the force is directly proportional to the product of the charges and inversely proportional to the square of the distance between them. The formula is F = (k * q1 * q2) / r2, where k is the Coulomb's constant, q1 and q2 are the charges, and r is the distance between them.

## 3. Can two point charges with the same sign attract each other?

No, two point charges with the same sign will always repel each other. This is because like charges repel and opposite charges attract, according to the law of electrostatics. This is also reflected in the formula for calculating the force of repulsion, where the charges have to be multiplied together.

## 4. How does the distance between two point charges affect the force of repulsion?

The force of repulsion between two point charges is inversely proportional to the square of the distance between them. This means that as the distance between the charges increases, the force of repulsion decreases. This is because the electric field, which is responsible for the force, weakens as the distance increases.

## 5. Are point charges used in real-life situations?

While point charges are a theoretical concept, they are used in real-life situations to model the behavior of electric charges. For example, the point charge model is used to calculate the electric field and force between charged particles in an atom. It is also used in the study of electric fields and forces in capacitors and other electronic devices.

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