The discussion centers on the calculation of the magnetic field inside a solenoid using Ampere's Law. Participants clarify that while one can compute the magnetic field from individual loops of current and sum them, this approach is more complex than directly applying Ampere's Circuital Law. The consensus is that Ampere's Law provides the total magnetic field generated by the current enclosed by the loop, negating the need for additional calculations from other cross sections of the solenoid.
PREREQUISITESPhysics students, electrical engineers, and anyone interested in understanding magnetic fields and their calculations in solenoids.
Limddong said:I think the real magenetic field is sum of the magnetic fields calculated in each cross section of solenoid with various angle and same center axis when i apply Ampere's law. (Imagine the cross section contains a part of center line of the solenoid) Please let me know why we don't do like that. :)
Thanks for answering my question! Yes, the 'real' is not appropriate word. 'Total' would be appropriate.ZapperZ said:I'm not clear what you are saying here, especially by the phrase "real magnetic field". Were you calculating an "unreal" magnetic field via other means?
There's nothing to stop you from calculating the magnetic field field at the center of a single circular loop of current, and then summing it up as you add more and more loops to form a solenoid. You'll get the same answer as applying the Ampere's Circuital method. But using the former is a lot more work!
This is no different than using Gauss's law for highly-symmetric situation to find the E-field, instead of applying Coulomb's law and doing all those nasty integrations.
Zz.
Limddong said:Ampere's law gives us just some magnetic field that is generated by current 'inside' the ampere circuital. That means the magnetic field i got from a cross section of a solenoid by Ampere's law is not total magnetic field.