# Cube Electric Field: Are Intersections Uniformly Distributed?

• bocobuff
In summary, the conversation discusses the distribution of field lines in a cube with a positive charge at its center. There is a debate on whether the intersections of the field lines with a side of the cube are uniformly distributed or not. The discussion also explores the relationship between the density of the field lines and the distance from the charge, using the analogy of a sphere inscribed in a cube. The conclusion is that the density of the lines is less on the cube compared to the sphere, except at the points where the sphere touches the cube.
bocobuff

## Homework Statement

A positive charge is located at the center of a cube.
Are the intersections of the field lines with a side of the box uniformly distributed across that side? Explain

## The Attempt at a Solution

I'm trying to picture this in my head and I'm getting stuck. I know the field lines in the corners are further away from the charge than the lines in the center of the cube face. But I can't determine if more lines would be coming into the corner of the face than the center, which would be perpendicular to the charge. Also, if the field lines did all intersect uniformly, wouldn't it be a sphere rather than a cube? I keep trying to visualize it like a golf ball in a kleenex box with lines coming out of the all dimples but I think I'm really over-thinking this one. Help if you can. Thanks.

The corners are how much farther away than the middle of a face?

a/2 as opposed to √ 3*a/2

If the density of the lines is proportional to strength ...

and the greater the distance, the less the strength?

I've drawn a circle inscribed in a square, but I'm thinking of a sphere inscribed in a cube. The field line density around the sphere is uniform, N/Ss where N is the number of lines and Ss the surface area of the sphere.

The same N lines go through the enclosing cube so its density averages N/Sc.
But Sc > Ss so N/Sc < N/Ss. Less dense on the cube, on average.
However, at or near those points where the sphere touches the cube, the density is the same as on the cube - greater than the average on the cube.

In one corner you have N/4 lines coming out of the quarter sphere and then going through a quarter of the cube. The surface area of the quarter cube > surface area of the quarter sphere. Therefore the density of the lines is less on the cube than on the sphere. Except at or near the points where the sphere touches the cube and the line density of the cube is equal to that on the sphere.

## 1. What is a cube electric field and how is it different from a regular electric field?

A cube electric field refers to the electric field present within a cube-shaped region. It is different from a regular electric field in that it is uniform, meaning that the magnitude and direction of the electric field is the same at every point within the cube.

## 2. How is the electric field distributed at the intersections of a cube?

The electric field at the intersections of a cube is uniformly distributed. This means that the magnitude and direction of the electric field is the same at every intersection point.

## 3. What factors can affect the uniform distribution of the electric field at the intersections of a cube?

The uniform distribution of the electric field at the intersections of a cube can be affected by the shape and size of the cube, as well as the electric charge and distance of the source of the electric field.

## 4. Why is it important to know if the intersections of a cube have a uniformly distributed electric field?

Knowing if the intersections of a cube have a uniformly distributed electric field is important for accurately predicting and understanding the behavior of electric charges within the cube. It can also help in designing and optimizing electrical systems.

## 5. How can the uniform distribution of the electric field at the intersections of a cube be measured?

The uniform distribution of the electric field at the intersections of a cube can be measured using an electric field sensor or by calculating the electric field at various points within the cube using mathematical equations.

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