Coulombs Law find q (charge)

In summary, the conversation discusses entering equations in a text box and solving for a common factor in an equation. The speaker also notes a small discrepancy in their calculations.
  • #1
th77
16
0
I attached my message and the problem in a Word document because I don't know how to enter equations in this text box.

Thanks for your help
 

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  • #2
Yeah your working is generally fine.

You can assign q4 a value, but it doesn't matter since it is a common factor throughout the whole equation. So what you do is you divide the LHS and RHS of your equation by q4. This leaves:

[tex]\frac {kq_4q_1} {q_4 (r_1_4)^2} - \frac {kq_4q_2} {q_4 (r_2_4)^2} + \frac {kq_4q_3} {q_4(r_3_4)^2} = 0/q4[/tex]

ie [tex]\frac {kq_1} {(r_1_4)^2} - \frac {kq_2} {(r_2_4)^2} + \frac {kq_3} {(r_3_4)^2} = 0 [/tex]

Anyway even doing it your way you should have got the same value as me, but you didn't. I got something closer to -4*10^-5 C (this isn't the answer). The actual answer is slighty more than -4*10^-5 C. So you must have made a simple calculating error.
 
  • #3
!

Coulomb's Law is a fundamental equation in electromagnetism that describes the force between two charged particles. It states that the magnitude of the force (F) between two point charges (q1 and q2) is directly proportional to the product of their charges and inversely proportional to the square of the distance (r) between them, as shown in the equation:

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

In order to find the charge (q) of a particle, we can rearrange this equation to solve for q:

q = (F * r^2) / (k * q2)

Where k is the proportionality constant, also known as the Coulomb's constant, and has a value of approximately 9 × 10^9 N * m^2 / C^2.

To find the charge, we need to know the magnitude of the force (F) between the two particles and the distance (r) between them. Once we have these values, we can substitute them into the equation and solve for q.

It is important to note that Coulomb's Law only applies to point charges, meaning that the particles are infinitely small and their size and shape do not affect the force between them. In real-life situations, where the charges have a finite size and shape, we need to use more complex equations to calculate the force.
 

1. What is Coulomb's Law?

Coulomb's Law is a fundamental law of physics that describes the electrostatic force between two charged particles. It states that 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.

2. How do you calculate the force between two charges using Coulomb's Law?

The force between two charges can be calculated using the formula F = (k * q1 * q2) / r^2, where F is the force in Newtons, k is the Coulomb's constant (9 x 10^9 N*m^2/C^2), q1 and q2 are the charges in Coulombs, and r is the distance between the charges in meters.

3. How do you find the charge of a particle using Coulomb's Law?

To find the charge of a particle using Coulomb's Law, you need to know the force between the particle and another known charge, as well as the distance between them. Rearranging the formula F = (k * q1 * q2) / r^2, you can solve for q1 or q2 depending on which charge is known.

4. What are the units of charge in Coulomb's Law?

The units of charge in Coulomb's Law are Coulombs (C). One Coulomb is equal to the charge of approximately 6.24 x 10^18 protons or electrons, which are the fundamental units of charge in the atom.

5. Can Coulomb's Law be applied to objects with non-point charges?

Coulomb's Law is based on the assumption that the charges are point charges, meaning they have no size or dimension. While it can still be used to approximate the force between objects with non-point charges, it becomes less accurate as the size of the charges increases. In these cases, more advanced equations and calculations may be needed.

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