# Changing electric field generating magnetic field

• arlesterc
In summary, the conversation discusses the concept of a changing electric field in relation to the creation of a magnetic field. It is clarified that the electric field does not necessarily need to reverse in order to create a magnetic field, it can also simply increase and decrease. This is not always explicitly stated in materials on the topic. The conversation also mentions that this concept is the basis of generating an electromagnetic wave, and that a steady DC current will only generate static electric and magnetic fields.

#### arlesterc

I would very much appreciate a clarification on what is meant by a changing electric field in the context of statements such as 'a changing electric field creates a changing magnetic field'. My question is does the electric field actually need to reverse as a lot of examples show where two charged particles change places so that the force changes direction or can it be that a magnetic field can be created by an electric field that is simply increasing and decreasing but not reversing. So does it have to be alternating current that induces magnetism or can just a changing amount of current cause magnetic fields. Perhaps another way of describing my question is to think of the electric field as either a sinusoidal wave - the alternating electric field idea - versus a half-sinusoidal wave - only the top or bottom of a sinusoidal wave - so that the field is increasing and decreasing from 0 to whatever height but never crossing the horizontal axis. In that situation the field is increasing/decreasing but not 'reversing' - would that fluctuation create a corresponding magnetic field? Or does it have to be the sinusoidal case for a magnetic field to be created?

arlesterc said:
My question is does the electric field actually need to reverse
No. (By "reverse" you mean change direction. Not needed.)

arlesterc said:
or can it be that a magnetic field can be created by an electric field that is simply increasing and decreasing but not reversing.
Yes.

Thanks for the quick and definitive response. This point was not made clear in a lot of material I saw - it always had reversal of direction - so negative and positive charges swapping repeatedly. That being said what difference does that particular scenario make as to the simply increasing/decreasing example?

arlesterc said:
Thanks for the quick and definitive response. This point was not made clear in a lot of material I saw - it always had reversal of direction - so negative and positive charges swapping repeatedly. That being said what difference does that particular scenario make as to the simply increasing/decreasing example?
just to be clear ...

arlesterc said:
changing electric field in the context of statements such as 'a changing electric field creates a changing magnetic field'.

that is the basis of the generation of an electromagnetic wave, the charges ( electrons) need to be accelerating

A steady DC current will generate static electric and magnetic fields

## 1. How does a changing electric field generate a magnetic field?

According to Maxwell's equations, a changing electric field will always induce a magnetic field. This phenomenon is known as electromagnetic induction and is the basis for many technologies, including generators and transformers.

## 2. Can a constant electric field generate a magnetic field?

No, a constant electric field alone cannot generate a magnetic field. A changing electric field is required for electromagnetic induction to occur.

## 3. How are the electric and magnetic fields related?

The electric and magnetic fields are intimately connected and form the electromagnetic field. Changes in one field will always induce changes in the other field, creating a self-sustaining system of energy.

## 4. How do changing electric fields and magnetic fields affect each other?

A changing electric field will generate a magnetic field, and a changing magnetic field will generate an electric field. This relationship is described by Faraday's law and is the basis for many applications, such as wireless charging and radio communication.

## 5. What are the practical applications of changing electric fields generating magnetic fields?

The ability to generate magnetic fields through changing electric fields has numerous practical applications. Some examples include electric motors, generators, transformers, and electromagnetic devices such as MRI machines and particle accelerators.