# Electric fields vs magnetic fields?

• Ascendant78
In summary, the conversation discusses the relationship between electric fields and magnetic fields. The speaker initially asks their professor about using the Lorentz Force Law and receives a response stating that there is no need to consider an electric field because there is only a magnetic force from the current in the wire. However, the speaker references multiple sources stating that a moving charged particle always has both a magnetic and electric field. They question whether there is always an electric field present when there is a magnetic field and receive clarification that in the case of an uncharged wire, the electric fields of the electrons are cancelled out by the protons, resulting in only a magnetic field. The conversation ends with the speaker thanking the other person for their clarification.
Ascendant78
Electric fields vs magnetic fields?

Ok, so in class last week, I had asked my professor about using the Lorentz Force Law to solve a particular problem. When he responded with "we only have a magnetic force from the current in the wire, so we don't have to worry about an electric field," that completely threw me for a loop.

A quote directly from our course's textbook, "All moving charged particles create magnetic fields... This is in addition to the electric field that is always present surrounding charged particles." A quote from another textbook, "A moving charge always has both a magnetic and electric field." Based on these statements and other external materials I read regarding the matter, I thought that whenever you have a magnetic field (excluding permanent magnets), you always have an electric field? I know I have read this in at least one or two other places as well, but maybe I'm just missing something here? If someone could clarify, I'd appreciate it.

The wire is uncharged. All of the electric fields of the electrons are canceled out by the electric fields of the protons. However, since the electrons are moving and the protons are not the magnetic field of the electrons is not canceled out. Therefore, you get a magnetic field and no electric field.

1 person
Your wire is uncharged, right? Then there is no net electric field from it.

1 person
Ok, I wasn't aware the no matter how much current flows through the wire, the proton to electron ratio is still always balanced. That was where my problem was... well that and misunderstanding the statements regarding charges and their fields. Thanks.

Well, it's true that whenever you have a magnetic field, there is also an electric field present. However, the strength and direction of the electric field may vary depending on the situation. Let's break it down.

Electric fields are created by electric charges. When a charge is stationary, it creates a static electric field. But when a charge is moving, it also creates a magnetic field. This is because the motion of a charge creates a current, and currents are what generate magnetic fields. So, in a way, electric fields and magnetic fields are interconnected.

Now, when we talk about "magnetic fields" in your problem, it sounds like we are specifically referring to the magnetic field created by a current in a wire. In this case, the electric field generated by the moving charges in the wire is negligible compared to the strength of the magnetic field. This is why your professor said you don't have to worry about it - because it's so small that it can be ignored for the purposes of your problem.

However, in other situations where the electric field is not negligible, both the electric and magnetic fields must be taken into consideration. For example, in the case of an electromagnetic wave, both fields are essential for its propagation.

So, in summary, electric fields and magnetic fields are both present whenever there is a moving charge, but in some cases, one may be much stronger than the other and can be ignored. It's important to understand the relationship between the two and how they work together in different scenarios. I hope this helps clarify things for you!

## 1. What is the difference between electric fields and magnetic fields?

Electric fields are created by stationary or moving electric charges, while magnetic fields are created by moving electric charges or by magnetic dipoles. Electric fields act on particles with electric charge, while magnetic fields act on particles with magnetic dipole moment.

## 2. How are electric and magnetic fields related?

Electric and magnetic fields are related through Maxwell's equations, which describe the behavior of electromagnetic fields. Specifically, a changing electric field can create a magnetic field, and a changing magnetic field can create an electric field.

## 3. Which one is stronger, electric or magnetic field?

The strength of an electric or magnetic field depends on the distance from the source and the magnitude of the source. In general, electric fields are stronger than magnetic fields, but this can vary depending on the specific situation.

## 4. Can electric and magnetic fields exist separately?

No, electric and magnetic fields are always interconnected. Whenever there is an electric field, there is also a magnetic field and vice versa. This is known as electromagnetic coupling.

## 5. How do electric and magnetic fields affect matter?

Electric fields can exert a force on charged particles, causing them to move. This is the basis for electricity and the functioning of many electronic devices. Magnetic fields can also exert a force on moving charged particles, and can also cause certain materials to become magnetized.

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