Finding magnitude of two charge given midpoint

In summary: Using the given information, you can set up a system of equations and solve for QA and QB. In summary, you need to use a different equation and solve a system of equations to find the magnitude of A and B.
  • #1
paulie
13
0

Homework Statement


Two positive point charges, A and B are 6m apart. The electric field intensity at point C, midway between the two charges is 5 N/C directed towards B and the potential at the same point is 45V. Find the magnitude of A and the magnitude of B.

Homework Equations


E = kQ/r2

The Attempt at a Solution


From what I visualize it:

(+A)<---3m--->(-C)<---3m--->(+B)

Using E = kQ/r2 where Q=Er2/k

Q = (5 N/C)(3 m)2 / (9x109 Nm2/C2) = 5x10-9C

which is the answer for A and B I suppose? But the answer key tells me that the answer in A is twice the B. How come? I'm quite confuse on how this works.
 
Physics news on Phys.org
  • #2
paulie said:

Homework Statement


Two positive point charges, A and B are 6m apart. The electric field intensity at point C, midway between the two charges is 5 N/C directed towards B and the potential at the same point is 45V. Find the magnitude of A and the magnitude of B.

Homework Equations


E = kQ/r2

The Attempt at a Solution


From what I visualize it:

(+A)<---3m--->(-C)<---3m--->(+B)

Using E = kQ/r2 where Q=Er2/k

Q = (5 N/C)(3 m)2 / (9x109 Nm2/C2) = 5x10-9C

which is the answer for A and B I suppose? But the answer key tells me that the answer in A is twice the B. How come? I'm quite confuse on how this works.
The equation you applied is valid for the electric field of a single point charge. You have two charges, QA and QB, both contributing to the electric field and to the potential at point C.
 

FAQ: Finding magnitude of two charge given midpoint

1. How do I find the magnitude of two charges given their midpoint?

To find the magnitude of two charges given their midpoint, you can use the formula Q = k(d1d2)/(d1+d2), where Q is the magnitude of the charges, k is the Coulomb's constant, and d1 and d2 are the distances from the midpoint to each charge.

2. What is the importance of finding the magnitude of two charges given their midpoint?

Finding the magnitude of two charges given their midpoint can help determine the strength of the electric field at that point. This information is useful in understanding the behavior of charged particles and can also be applied in various practical applications such as in designing electrical circuits.

3. Can I use this formula to find the magnitude of any two charges?

Yes, you can use this formula to find the magnitude of any two charges as long as you have the distance between the midpoint and each charge. However, keep in mind that this formula assumes the charges are point charges and are not moving.

4. What are the units for the magnitude of two charges given their midpoint?

The units for the magnitude of two charges given their midpoint are typically Coulombs (C). However, if you are using different units for distance, such as meters or centimeters, you may need to adjust the units accordingly.

5. Is there a graphical method for finding the magnitude of two charges given their midpoint?

Yes, you can also use a graphical method to find the magnitude of two charges given their midpoint. This involves drawing a diagram with the midpoint and the two charges, and then using the Pythagorean theorem to calculate the distance between the midpoint and each charge. Once you have the distances, you can use the formula mentioned in the first question to find the magnitude of the charges.

Back
Top