What is the force between the two point charges?

In summary, the electrostatic force between two point charges is 5.7*10^-4N. The force changes when one of the charges triples and the distance between the points doubles. By using Coulomb's Law, which states that the electrostatic force is equal to the product of the charges divided by the square of the distance between them, we can find the new force by plugging in the initial values and applying the changes to the formula. This results in a new force of 2.85^-4N.
  • #1
marshall4
50
0
The electrostatic force between two point charges is 5.7*10^-4N. The charge on one of the point charges triples and the distant between the points doubles. What is the force between the two point charges?
 
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  • #2
5.7*10^-4N/2 = 2.85^-4N What have i done wrong?
 
  • #3
What is Coulomb's law?
 
  • #4
Using Coulomb's Law you're given:

[tex]\vec{F_{e}} = k\frac{qQ}{r^2} \hat{r}
[/tex]

where [tex]q[/tex] and [tex]Q[/tex] are two different point charges.

By tripling one of the charges (it doesn't matter which one) and doubling the distance you now have:

[tex]\vec{F_{e}} = k\frac{3qQ}{(2r)^2}\hat{r}=k\frac{3qQ}{4r^2}\hat{r}[/tex]

You should now be able to find the force between the two charges by plugging in the initial values of the two point charges and the original distance r.


It always helps to work directly from the law or formula that's given.
 
  • #5
Originally posted by marshall4
The electrostatic force between two point charges is 5.7*10^-4N. The charge on one of the point charges triples and the distant between the points doubles. What is the force between the two point charges?

What rogue said is exactly right but it may still look confusing. Just look at the constants added to the formula. The original formula was this
[tex]\vec{F_{e}} = k\frac{qQ}{r^2} \hat{r}[/tex]

The new formula is this:

[tex]\vec{F_{e}} = k\frac{3qQ}{4r^2}\hat{r}[/tex]

The only things that changed are the 3 in the numerator and the 4 in the denominator.
Just multiply your original force by 3/4 and you should get the answer :)
 

1. What is the force between two point charges?

The force between two point charges is a measure of the attraction or repulsion between the two charges. It is calculated using Coulomb's Law, which states that the force is directly proportional to the product of the two charges and inversely proportional to the square of the distance between them.

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

The force between two point charges can be calculated using the equation F = (k*q1*q2)/r2, where k is the Coulomb's constant (8.98755 x 109 Nm2/C2), q1 and q2 are the magnitudes of the two charges, and r is the distance between them.

3. What is Coulomb's Law?

Coulomb's Law is a fundamental law of electrostatics that describes the force between two point charges. It states that the force is directly proportional to the product of the two charges and inversely proportional to the square of the distance between them.

4. Does the force between two point charges depend on their charges and distance?

Yes, the force between two point charges is directly proportional to the product of their charges and inversely proportional to the square of the distance between them. This means that as the charges increase, the force between them increases, and as the distance between them increases, the force decreases.

5. Can the force between two point charges be attractive and repulsive?

Yes, the force between two point charges can be both attractive and repulsive depending on the sign of the charges. Like charges (both positive or both negative) will repel each other, while opposite charges (positive and negative) will attract each other.

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