Finding an electric field from a scalar field

In summary, the conversation discusses finding the scalar field that would produce a given electric field, as well as the process of integrating each component to find the potential function. It is mentioned that the partial derivatives of the potential function can be used to determine the unknown function, and that the components of the electric field only give information about certain terms in the potential function.
  • #1
Noone1982
83
0
Say I know an electric field

E = (yz - 2x)x-hat + (xz)y-hat + (xy)z-hat

How do I find the scalar field that would produce that? If I integrate each part I get

Vx = xyz - x^2
Vy = xyz
Vz = xyz

Vt = 3xy - x^2

To find E, I would take E = gradient cross the scalar field, but that would clearly not work. What I am doing wrong?
 
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  • #2
Pick any component you want and integrate. For instance, if you picked the x-component then your guess "answer" would look like [tex] V = xyz - x^2 + f(y,z), [/tex] where f is an arbitrary function of y and z. This is because you only know that the partial derivative of V with respect to x is equal to yz - 2x. To figure out what your function f is, make use of your information about the other two partial derivatives of V. Of course, V is still undefined up to a constant.
 
  • #3
Each component of the E-Field is the (-) derivitive of the scalar potential with THAT coordinate , yes E is the (-) gradient .

Notice that d(x^2)/dy = 0 , so that E_y cannot give info about purely "x" terms in V, (or x and z terms, either). Similarly, E_x gives no info about purely y or z terms.

Don't add the xyz terms, just make sure they all agree.
 
Last edited:
  • #4
Im still fuzzy on how to obtain the unknown function. Can you further explain?
 

1. What is the difference between a scalar field and an electric field?

A scalar field is a mathematical function that assigns a scalar value to every point in space. An electric field, on the other hand, is a vector field that describes the strength and direction of the force that a charged particle would experience at any given point in space.

2. How do you find the electric field from a given scalar field?

The electric field can be found by taking the negative gradient of the scalar field. This means finding the partial derivatives of the scalar field with respect to each coordinate direction (x, y, z) and multiplying them by -1 to get the x, y, and z components of the electric field vector.

3. What are the units of a scalar field and an electric field?

A scalar field is a dimensionless quantity, meaning it has no units. An electric field, however, is measured in units of force per unit charge, or newtons per coulomb (N/C).

4. Can a scalar field exist without an electric field?

Yes, a scalar field can exist without an electric field. Scalar fields can represent various physical quantities such as temperature, pressure, or density, while electric fields specifically describe the influence of electrically charged particles.

5. How is the electric field related to the potential of a scalar field?

The electric field is related to the potential of a scalar field through the equation E = -∇V, where V is the scalar potential. This means that the electric field is the negative gradient of the scalar potential, and the potential can be found by integrating the electric field.

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