Does a solenoid's magnetic flux change when a magnet's pole is moved away?

AI Thread Summary
A solenoid will have magnetic flux from an attached magnet's S pole even when another magnet's N pole is not nearby. The magnetic field lines loop back to the S pole, passing through the solenoid core due to its low reluctance compared to air. Induction in the solenoid coil occurs primarily when the N pole of the second magnet is moved near the solenoid. The presence of the attached magnet does not prevent induction from occurring, but its exact impact on the induction generated by the moving magnet is uncertain. Overall, the solenoid can still produce induction regardless of the presence of the attached magnet.
Salvador
Messages
505
Reaction score
70
Hi, I was wondering about a simple example.take a coil wound on a solenoid, one side of the solenoid core is permanently attached to a permanent magnet S pole, the other end of the solenoid core is not attached to any magnet.
Now I take another magnet turn it with the N pole facing the solenoid and move it near and then again away from the solenoid, I get induced current in the solenoid coil.my question is this, when the other magnet's N pole is not close or near the solenoid core does the solenoid core has magnetic flux in it from the S pole of the magnet that is attached to it's other side , or does flux only enter a certain material (low reluctance in this case) when the b field has an opposite pole to go into ?
 
Physics news on Phys.org
Salvador said:
my question is this, when the other magnet's N pole is not close or near the solenoid core does the solenoid core has magnetic flux in it from the S pole of the magnet that is attached to it's other side , or does flux only enter a certain material (low reluctance in this case) when the b field has an opposite pole to go into ?

Yes, the solenoid will have magnetic flux from the attached magnet pole passing through it even when the other magnet is nowhere nearby. These lines will eventually loop back around to the magnets north pole.
 
and the reason for that is probably because even without the other pole being there the field lines loop back to the other pole of the same magnet and they loop through the solenoid core because its reluctance to field is much less than that of air so the flux will always take that path no matter what right?

ok but then i have a question, does the flux being there in the core even without the other pole affect the coil sitting on the solenoid ? I assume no.I think only when the other pole is passed by the other side of the solenoid core only then the coil on it has induction correct?
so just by having one pole constantly attached doesn't ruin or change anything I can still move the other pole near the other side and get the same amount of induction that I would get when passing both poles of both magnets from each side ?
 
Salvador said:
so just by having one pole constantly attached doesn't ruin or change anything I can still move the other pole near the other side and get the same amount of induction that I would get when passing both poles of both magnets from each side ?

That I don't know. You'll certainly still get some amount of induction, but I don't now how having the magnet attached to the solenoid affects the induction generated by moving the 2nd magnet.
 
Thread 'Inducing EMF Through a Coil: Understanding Flux'
Thank you for reading my post. I can understand why a change in magnetic flux through a conducting surface would induce an emf, but how does this work when inducing an emf through a coil? How does the flux through the empty space between the wires have an effect on the electrons in the wire itself? In the image below is a coil with a magnetic field going through the space between the wires but not necessarily through the wires themselves. Thank you.
Thread 'Griffith, Electrodynamics, 4th Edition, Example 4.8. (Second part)'
I am reading the Griffith, Electrodynamics book, 4th edition, Example 4.8. I want to understand some issues more correctly. It's a little bit difficult to understand now. > Example 4.8. Suppose the entire region below the plane ##z=0## in Fig. 4.28 is filled with uniform linear dielectric material of susceptibility ##\chi_e##. Calculate the force on a point charge ##q## situated a distance ##d## above the origin. In the page 196, in the first paragraph, the author argues as follows ...
Back
Top