# Finding electric field between two charges

• joel amos
In summary, the conversation discusses two charges, Q1 = 4*10-8 and Q2 = 2.7*10-8, that are 3.25 m apart and the electric field magnitude halfway between them. The solution involves using the equation E = kQ/r2 and calculating the electric fields for each charge separately before subtracting them to get a final answer of 43.5 N/C. It is important to check for any calculation or conceptual errors when solving this problem.
joel amos

## Homework Statement

Two charges, Q1 = 4*10-8 and Q2 = 2.7*10-8 are 3.25 m apart.
What is the electric field magnitude halfway between them?

E = kQ/r2

## The Attempt at a Solution

E1= k (4*10-8C)/(1.63m)2
= 135 N/C
E2= k (2.7*10-8C)/(1.63m)2
= 91.4 N/C

135 N/C - 91.4 N/C = 43.5 N/C

Is this correct?

Yes. You will get somewhat different answers depending on how you round your numbers during the calculation.

Looks ok. Do you have a reason to doubt it?

It is best you don't rely on someone else to tell you if you are right or not.
Take this opportunity to practice :)

There are only two ways you are likely to be wrong in this problem:
1. you got the numbers wrong
2. you got the physics wrong

for 1 you just check your substitution
for 2 you go through your reasoning to see if your answer is consistent with the way charges behave.
When you start out doing this stuff it seems quite hard but you'll quickly get used to it.

Yes, your solution is correct. The electric field magnitude halfway between the two charges is 43.5 N/C. You have correctly used the equation E = kQ/r^2 to calculate the electric field due to each charge and then subtracted them to find the net electric field at the midpoint. Good job!

## 1. What is an electric field?

An electric field is a physical field that describes the influence that an electric charge has on other charges and objects in its vicinity. It is represented by a vector quantity, with both magnitude and direction. It is measured in units of Newtons per Coulomb (N/C).

## 2. How is the electric field between two charges calculated?

The electric field between two charges can be calculated using Coulomb's law, which states that the electric force between two charges is directly proportional to the product of their charges and inversely proportional to the square of the distance between them. The formula for calculating electric field is E = kQ/r^2, where k is the Coulomb's constant, Q is the charge of the source charge, and r is the distance between the two charges.

## 3. What is the direction of the electric field between two charges?

The direction of the electric field is determined by the direction of the force that the field would exert on a positive test charge placed at that point. The field lines point away from positive charges and towards negative charges.

## 4. Does the electric field between two charges depend on the medium between them?

Yes, the electric field between two charges depends on the medium between them. The presence of a medium can affect the electric field by altering the permittivity of the space between the charges. This is represented by the permittivity constant, ε, in the formula for calculating electric field.

## 5. What is the significance of finding the electric field between two charges?

Finding the electric field between two charges is important for understanding the interactions between electric charges. It allows us to predict the magnitude and direction of the electric force that would be exerted on a charge placed at a certain point. This information is crucial in many areas of science, including electromagnetism, electronics, and particle physics.

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