# Find the direction and magnitude of an electric field

• jmemo
In summary, to find the direction and magnitude of an electric field exerting a 4.65 ✕ 10−17 N westward force on an electron, you can use Coulomb's Law, E = kq/r^2, where E is the electric field, k is the Coulomb constant, q is the charge of the electron, and r is the distance between the electron and the source of the field. The Coulomb constant is not the same as the Coulomb force, and the given force value should be used in the equation to solve for the electric field.
jmemo
Homework Statement
Find the direction and magnitude of an electric field that exerts a 4.65 ✕ 10−17 N westward force on an electron. (Enter the magnitude in N/C.)
Relevant Equations
e=f/q or E=kq/r^2
Find the direction and magnitude of an electric field that exerts a 4.65 ✕ 10−17 N westward force on an electron. (Enter the magnitude in N/C.)

Last edited by a moderator:
Please show what you've tried so far. You must show an attempt. Relevant equations must be in your textbook or class notes. Please provide, thanks!

e=f/q or E=kq/r^2

4.65e-17/8.99e9

don'know if this how to do it

jmemo said:
e=f/q or E=kq/r^2
The first equation is the one you should be using. Can you explain what the symbols e, f and q stand for and what their numerical values are if given or known?

e= electric field 4.65e-17, q =test charge, and f coulomb force 8.99e9

jmemo said:
... f coulomb force 8.99e9
Where did you see this written down?
Check your textbook or see here for Coulomb's Law. You are confusing the Coulomb force with the Coulomb constant. They are not the same. Besides, where do you think the ##4.65\times 10^{-17}~\mbox{N}## fits in all this? What does it represent?

## 1. How is the direction of an electric field determined?

The direction of an electric field is determined by the direction of the force that a positive test charge would experience if placed in the field. The field lines always point away from positive charges and towards negative charges.

## 2. What is the magnitude of an electric field?

The magnitude of an electric field is a measure of the strength of the field at a particular point, and is represented by the force per unit charge. It is calculated using the equation E = F/q, where E is the electric field, F is the force, and q is the test charge.

## 3. How do you find the direction of an electric field using field lines?

Field lines are used to visually represent the direction of an electric field. The direction of the field at any point is tangent to the field line at that point. Field lines also show the relative strength of the electric field, with closer lines indicating a stronger field.

## 4. Can the direction of an electric field change?

Yes, the direction of an electric field can change depending on the location and orientation of the charges that create the field. The direction of the field is always determined by the direction of the force on a positive test charge, so if the location or orientation of the charges changes, the direction of the field will also change.

## 5. How is the magnitude of an electric field affected by distance?

The magnitude of an electric field decreases as distance from the source increases. This is because the electric field is spread out over a larger area, resulting in a weaker field. The relationship between the magnitude of the field and the distance is inversely proportional, meaning that as the distance increases, the magnitude decreases by the same factor.

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