What is change in the magnetic flux (delta B)?

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Discussion Overview

The discussion centers around the concept of change in magnetic flux (delta B), exploring its definition, implications in electromagnetic induction, and the behavior of magnetic domains in coils. Participants also touch on related principles such as Faraday's law and Lenz's law, as well as practical examples involving coils and magnetic fields.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant defines magnetic flux as \Phi=BA, where B is magnetic flux density and A is surface area, suggesting that changes in B lead to a rate of change of flux and induced emf according to Faraday's law.
  • Another participant proposes that as a magnet approaches a coil, the magnetic domains in the coil align with the magnetic field, and when the magnet is removed, the domains return to their original state, raising questions about the direction of magnetic flux.
  • Several participants inquire about determining the direction of magnetic flux in a coil, with one suggesting the right hand grip rule as a method for solenoids.
  • A participant introduces a practical example involving hula hoops and beads to illustrate the interaction of air flow and magnetic principles, referencing both Faraday's law and Lenz's law, and questions how increasing air flow can change the direction of bead movement.

Areas of Agreement / Disagreement

Participants express varying interpretations of magnetic flux and its implications, with some agreement on definitions but no consensus on the practical applications or the specific behavior of magnetic domains. The discussion remains unresolved regarding the practical implications of these concepts.

Contextual Notes

Participants have not fully resolved the assumptions regarding the behavior of magnetic domains or the specific conditions under which magnetic flux changes occur. The discussion also reflects varying interpretations of related laws and principles.

Physicsissuef
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What is change in the magnetic flux (delta B)? Like on this http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/emfchb.html"
 
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Well the magnetic flux is given by [itex]\Phi=BA[/itex] where B is magnetic flux density and A is the surface area.
So a field interacts with another magnetic field then the value of B changes and hence there should be a rate of change of flux. And by faraday's law, and emf is induced.
 
Is it like, when I approach magnet, than the magnetic domains of the coil get in line with the magnetic field of the magnet and when I get back the magnet, the magnetic domains of the coil are like in the first position? I mean, for the direction of the magnetic flux.
 
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Can somebody help me to determine the direction of the magnetic flux of the coil?is that, something to do with the aligning of the magnetic domains?
 
Physicsissuef said:
Can somebody help me to determine the direction of the magnetic flux of the coil?is that, something to do with the aligning of the magnetic domains?

A coil like a solenoid? if so then to determine the direction of the magnetic flux you need to use the right hand grip rule
 
rock.freak667 said:
A coil like a solenoid? if so then to determine the direction of the magnetic flux you need to use the right hand grip rule
But, I thought in practical way. What happens with the flux?
 
And can you please explain me this quote from "Newton Ask A scientist"
These days, most hula hoops have beads in them. Let's pretend that if
the beads move inside the hoop they will generate wind through the hoop.
Let's say if they go clockwise, they generate a wind going in the direction
a screw would go if the beads were turning it. Let's say if you increase
the amount of air going in that same direction through the hoop, the beads
will feel forced to move (so far we have Faraday's law) counter-clockwise
(now we've added Lenz's law).
How is it possible that increasing the amount of air will change the direction of the beads?
Here is the whole topic:
http://www.Newton.dep.anl.gov/askasci/phy99/phy99x61.htm
 

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