Rotating Disk in Magnetic Field

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SUMMARY

The discussion centers on deriving the circuit equation for a rotating conductive disk in a magnetic field. The equation presented is ir = emf + v(a) - v(b), where 'r' represents the resistance of the disk. Participants clarified that the Lorentz force determines the distribution of positive and negative charges, with positive charges accumulating at point B due to the radial direction of the Lorentz field. The relationship between voltage and resistance is further explained through Ohm's law.

PREREQUISITES
  • Understanding of electromagnetic theory, specifically the Lorentz force.
  • Familiarity with circuit analysis, including Ohm's law.
  • Knowledge of the behavior of conductive materials in magnetic fields.
  • Basic concepts of voltage and resistance in electrical circuits.
NEXT STEPS
  • Study the principles of electromagnetic induction and its applications.
  • Learn about the mathematical derivation of the Lorentz force equation.
  • Explore advanced circuit analysis techniques for rotating systems.
  • Investigate the effects of varying magnetic fields on conductive materials.
USEFUL FOR

Students and professionals in electrical engineering, physicists studying electromagnetism, and anyone interested in the dynamics of conductive materials in magnetic fields.

NewEinstein
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Hi I am having a difficulty understanding how to write the circuit equation inside a disk which rotates in magnetic field.
the disk is made of conductor material.
the resistance of the disk is: r
the answer is: ir=emf+v(a)-v(b)
if someone could explain it would be great!
and how do i know where is the positive charge and negative charge
thanks!
upload_2015-9-5_14-37-57.png
 
Last edited:
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You can tell where the positive charges are by the direction of the Lorentz force that any charge has, with the direction of every charge's instantaneous velocity is clear.
The equation just unveils the voltage between A and B?
 
tommyxu3 said:
You can tell where the positive charges are by the direction of the Lorentz force that any charge has, with the direction of every charge's instantaneous velocity is clear.
The equation just unveils the voltage between A and B?
oh thank you now i got it the lorentz field is always in the radial direction out of the disk so the positive charge is on b..
and yes that is the voltage between A and B but i also got it now from Ohm`s law
 

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