How is the Induced Magnetic Field Inside a Coil Determined?

[mad_monkey_j]

Homework Statement

What is the induced magentic field inside the coil?
Attached image shows the coil and direction of rotation.

Homework Equations

Right hand rule of some sort.

The Attempt at a Solution

Not sure what hand rule to use to find the induced field in the coil. What would you consider the rotation as? I know the rules involving the field, the force and the current.

 

[ehild]

What do those dots represent in the figure?

ehild

 

[mad_monkey_j]

That the field is coming out of the page.

 

[ehild]

Magnetic or electric?

ehild

 

[mad_monkey_j]

I would assume magnetic.

 

[ehild]

Is that the original text of the problem? Is not the induced electromotive force that you have to find? What equations have you learned about the interaction of magnetic field and current?

ehild

 

[mad_monkey_j]

That's the second part, before hand i had to calculate change in emf and the likes. The only way to solve this would be using one of the hand rules. E.g Left hand rule, first right hand rule and second right hand rule

 

[mad_monkey_j]

Any help at all?

 

[ehild]

You need to show an attempt to solve the problem. What those rules state and what do they mean in this case.

ehild

 

[mad_monkey_j]

How can i show an attempt at the solution if there isn't an equation to solve it. As i have stated numerous times it is a hand rule.

 

[ehild]

There are no numerical data so you can find the direction of the induced field only. I can not know what hand rules you learned or think of. Sorry, I can not help more.

ehild

 

[mad_monkey_j]

That's what I'm trying to find the direction of the induced field, and don't know which of the hand rules (Left hand rule, first right hand rule and second right hand rule) to use.

 

[ehild]

What do those rules say?

ehild

 

[mad_monkey_j]

Left hand rule:
Index finger is velocity, palm is force and thumb is field direction.
First right hand:
Thumb is current and curled fingers is field direction
Second right hand:
Thumb is velocity, fingers are field and palm is force.

 

[ehild]

Well, but velocity of what, what force and what field?

ehild

 

[mad_monkey_j]

The velocity is the direction it moves, force is the direction the field moves a particle and field is the dirction of the dots on the page, in this case out of the page.

 

[ehild]

What is that "it" that moves?

ehild

 

[mad_monkey_j]

Depends on the question, usually a particle or a rod. Don't know how to deal with the part of the coil rotating.

 

[ehild]

The electrons are inside the wire or rod which moves, so they have the same velocity. The rules apply if the velocity of a charged particle is perpendicular to the magnetic field and give the force exerted on the particle. As it is shown now, the velocity of each wire segment is just parallel with the magnetic field lines, and there is no force then, but as you turn the frame a bit, there will be a component of velocity which is normal to the magnetic field lines and you can find the force acting to the charges inside the wires. What is the direction of this force exerted on the electrons in each piece of wire?
What motion of electrons will set up by this force?

ehild

 

[mad_monkey_j]

So the electrons will move left causing them to travel clockwise?

 

[ehild]

Well, the force is opposite to the electrons, but the current is opposite to the drift velocity of the electrons, so the current is clockwise, you are right. Now you have current in the frame, what about its magnetic field? Which hand rule do you have to apply?

ehild

 

[I like Serena]

Hi mad_monkey_j!

Is it possible that the question is to calculate the induced magnetic force instead of the induced magnetic field?

 

[mad_monkey_j]

So the induced field will be out of the page according the the first right hand rule.

 

[ehild]

So the induced field will be out of the page according the the first right hand rule.

Apply the first right hand rule for current loop. Your curved fingers in the direction of the flow of current, thumb in the direction of the magnetic field.

ehild

 

[mad_monkey_j]

used my left hand lol, thanks.