Understanding the Strength of an Electric Field

• danago
In summary, the conversation discusses the equation for the strength of an electric field, E = F/q, and how it can be confusing since the force, F, is dependent on the distance of the test charge from the source charge. It is clarified that this equation is specific to a point in space and that the electric field, represented by E field lines, is a vector field with a different value at each point in space. Therefore, the strength of an electric field is relative to a specific point and cannot be stated as a constant value for all points in space.
danago
Gold Member
Hey. Was just reading through some notes, and found the equation for the strength of an electric field:

$$E = \frac{F}{q}$$

Im a little confused. How can an electric field have a single value that can define its strength, if the force, F, on the test charge, q, is dependant upon the distance of the test charge from the source charge?

Dan.

PS. This isn't a homework question, just something that i came across that had me confused.

E = F/q is specific to a point in space with a given force. Electric field, relative to a point charge does depend on distance in the same way you would expect, E = q/r^2 . The only time you would get a constant E that applied to every point in a space would be in a situation like that which occurs between the plates of a parallel plate capacitor

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ok. So really, at a basic level, there is no way to state the strength of an electric field, without it being relative to a specific point?

The electric field is just that -- a field. You represent it with E field lines. The E field is a vector field. At any point in space, E has a vector value that points in the direction of the E field lines in that area.

Ok makes sense. Thanks for the help.

1. What is an electric field?

An electric field is a physical quantity that describes the influence of an electric charge on other charges in its vicinity. It is represented by a vector, whose magnitude and direction indicate the strength and direction of the force that a charge would experience if placed in that field.

2. How is the strength of an electric field measured?

The strength of an electric field is measured in units of volts per meter (V/m). This unit represents the amount of electric force that a charge of one volt would experience per unit of distance.

3. What factors affect the strength of an electric field?

The strength of an electric field depends on two main factors: the magnitude of the electric charge creating the field and the distance from that charge. The closer the charge, the stronger the field, and the larger the charge, the stronger the field.

4. How does the direction of an electric field affect its strength?

The direction of an electric field is important because it determines the direction in which a test charge would move if placed in the field. The strength of the field is strongest in the direction of the electric force and weakest in the opposite direction.

5. How can the strength of an electric field be visualized?

One way to visualize the strength of an electric field is by using field lines. These are imaginary lines that show the direction and strength of the field at different points in space. The closer the lines are together, the stronger the field is in that region.

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