What does change in magnetic flux mean? How can you change magnetic flux? How does a change in magnetic flux influence a current of electrons (electricity)?
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3 Answers
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It means the magnetic lines of force are moving, or expanding and contracting,. Like when a transformer is changing its magnetic flux as the current with in it switches poles from negative to positive and back aka alternating current AC current, as in not DC current. When a conductor cuts a line of magnetic force it induces a voltage, whether by the moving of the conductor or moving of the flux, either or.
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Magnetic flux is basically the surface integral of the normal component of the magnetic field passing through that particular surface. Or to explain more simply, taking the concept of magnetic field lines into consideration, it is the number of magnetic field lines passing through a given area of the surface, where magnetic field lines is a pseudo concept just taken into consideration for simplicity.
More the crowded the magnetic field lines more is the magnetic intensity in that particular area you consider.
A change in magnetic flux implies a change in the number of magnetic field lines passing through a given area.Saying more profoundly,a change in the result of the surface integral. So,from the equation of magnetic flux(given in the above image) a change in magnetic flux can be gained either be changing the magnetic field through the given area or by changing the area of the given body or by changing the angle between the magnetic field and the area vector.
The change in magnetic flux through a coil inducing an emf across it can be explained as follows:
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$\begingroup$ Questions. So there is an induced EMF across points a and b. Where a is positive and b is negative. 1. Which direction is the actual current flowing through the wire, b to a or a to b? 2. What is the direction of the actual current flow. 3. Is this electron current flow or positive current flow? 4. Does the induced EMF produce an induced (secondary?) current that opposes the actual current? 5. If so, what is the direction of the induced current. 6. Is this electron current flow or positive current flow? $\endgroup$– mrbeanMar 27, 2022 at 18:56
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All magnetic flux stems from movement of electric charge, so it makes sense that it can stimulate movement of electric charge. A permanent magnet has a certain magnetic field around it that is the result of an alignment of magnetic domains, which in turn arise from the spin alignment of a bunch of electrons. The term flux is defined as the amount of something going through an area. If you imagine a box near a magnet and imagine the field lines, see that some of them are going through your box (no matter how you oriented things that should be so because the field extends out infinitely). Now if you moved the box or the magnet in anyway and the amount of field density intersected by the area of the box changes, then you've "changed the flux" of the box, so if the box is actually a copper loop, then current should flow according to the laws deduced by Maxwell, Faraday, and others.
answered May 26, 2017 at 5:39