# What is magnetic field made up of?

1. Sep 25, 2016

### Zheng_

1. The problem statement, all variables and given/known data
A magnetic field is made up of

A) positive and negative charges.

B) magnetic domains.

C) flux lines.

D) magnetic poles.

2. Relevant equations

3. The attempt at a solution

I thought magnetic field is made up of.. nothing ? Or does it mean 'What does magnetic field produced by'?

2. Sep 26, 2016

### Orodruin

Staff Emeritus
The question does not make sense as it stands. The magnetic field is a fundamental entity in classical electrodynamics.

3. Sep 26, 2016

### Drakkith

Staff Emeritus
Is this an actual homework problem? If so, I'd say 3 of the options are not the magnetic field itself, but something else.

4. Sep 26, 2016

### Zheng_

Yes. And it's also a question of previous years exam.

5. Sep 26, 2016

### Zheng_

That why I'm so confused about what does it mean.

6. Sep 26, 2016

### Orodruin

Staff Emeritus
I would say none of the options make sense. This is a question written by someone who does not know what they are doing.

7. Sep 26, 2016

### Zheng_

Ok thanks for the help. I guess I will ask my teacher on the next class.

8. Sep 26, 2016

### Zheng_

Yes. And it's also a question from previous years exam.

9. Sep 26, 2016

### Orodruin

Staff Emeritus
Just to be clear here. I suspect the answer your teacher wants is "magnetic field lines" (the others are sources for the magnetic field). This is about as accurate as saying that a force is made up of a vector arrow (i.e., not accurate at all). Vector arrows and field lines are visual/mathematical (depending on whether we just use the picture or also the maths) tools that we use to visualise and describe the concepts of forces and fields, they are not what the forces/fields are made up from in any way.

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