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Associate

Join Date: Feb 2017
Posts: 50

# FBI Mnemonics And Right Hand Rule Do Not Work Together?

03/01/2017 2:11 PM

Apprently ive forgotten lots from school and was just messing around today.

Everyone knows through lenzs law and the right hand rule that a current going through a wire will produce a field according to the right hand rule

I discovered today or remembered more likely that the FBI Mnemonics for a motor apparently violate this.

Can someone confirm this?

If you were to draw a simple loop with two poles north and south the two laws violate each other. I thought the right hand rule always held true for current through a wire.

Apparently im loosing my mind

To use the left hand rule for motors you must have to know more then just the direction of current because you could hold your left hand more then one way.

What am i missing here.

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Associate

Join Date: Feb 2017
Posts: 50
#1

### Re: FBI Mnemonics And Right Hand Rule Do Not Work Together?

03/01/2017 3:31 PM

Nevermind, i figure out what the issue but will leave this here incase someone else is curious

The issue is that the Field in the left hand rule is not the field that is created from the current through a wire but the direction of the field that is created via the armature.

This will give you the correct result.

Guru

Join Date: Apr 2010
Posts: 5901
#2

### Re: FBI Mnemonics And Right Hand Rule Do Not Work Together?

03/01/2017 5:39 PM

The first diagram is correct, showing the relationship between current flow and magnetic flux.

In the second diagram, the B field is external, from another source. The field from current flowing in the wire interacts with this field to generate the force as shown.

Guru

Join Date: Sep 2016
Posts: 778
#3

### Re: FBI Mnemonics And Right Hand Rule Do Not Work Together?

03/02/2017 11:26 AM

Why it always goes like that? Why is EM wave right handed?