Faraday's vs Ampere's Laws and current density

Click For Summary
SUMMARY

This discussion focuses on the relationship between Faraday's Law and Ampere's Law in the context of electromotive force (EMF) and current density. It confirms that a time-varying magnetic field induces an EMF, which in turn generates current density in a medium, represented by the equation J = σE. The conversation also includes practical experiments involving a coil and solenoid, detailing induced EMF measurements at frequencies of 13.24 MHz and 13.56 MHz, with specific voltage outputs recorded. The results indicate significant variations in induced EMF based on frequency and coil configurations.

PREREQUISITES
  • Understanding of Faraday's Law of Electromagnetic Induction
  • Familiarity with Ampere's Law and its applications
  • Knowledge of current density and its relationship with electric field and resistivity
  • Basic principles of electromagnetic fields and circuits
NEXT STEPS
  • Explore the mathematical derivation of Faraday's Law and its applications in circuit design
  • Investigate the effects of frequency on induced EMF in coils and solenoids
  • Learn about the practical applications of current density in electrical engineering
  • Study the impact of resistivity on current flow in various materials
USEFUL FOR

Electrical engineers, physics students, and anyone involved in electromagnetic theory and applications, particularly those working with coils and solenoids in circuit design.

VictorVictor5
Messages
13
Reaction score
0
Greetings all,

I know that Faraday's and Ampere's law are related by M.E., but can I say the following?

By Faraday’s Law, a time varying magnetic field induces an electromotive force, which produces an electric current density in a media.

Up until EMF, that's Faraday's, but is the rest of the sentence true? I would assume yes since J=sigma*E, or E=J/sigma to keep it in line with using Del X E = -jwB, or Del X J/sigma=-jwB.

Just trying to confirm.

Thanks!
VV5
 
Engineering news on Phys.org
The EMF can produce a current if there is a circuit. The current will depend on EMF and resistance. The current density will depend on E and resistivity.
 
On the right side of Del X E you would have the negative of the time derivative of B. The substitution for E looks fine.
 
Thanks to both!
 
hi
i have a coil of three turns and the spacing between the turns is 5 mm. i feed the coil with a signal of 13.24 MHz. and i put a solenoid of 3 mm radius 21 cm away from the coil to induce an emf. the solenoid has 23 number of tuns, 28 mm length. the induced emf is 280 mm V (rms) which is almost 10 times more than what i calculated. when i diconnect the coil from the signal generator, the induced voltage is 128 mmV(rms). the net emf= 152 mmVrms..
when the feeding freequency increased to 13.56 MHz and the solenoids number of turns decreased to 22. induced emf =460 mmV (rms) discennected 213 mmV. net induced emf=247 mV (rms).
can any recomand me any think.
thank you
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
699
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 11 ·
Replies
11
Views
3K
  • · Replies 15 ·
Replies
15
Views
2K
  • · Replies 5 ·
Replies
5
Views
1K
  • · Replies 7 ·
Replies
7
Views
2K
Replies
10
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 25 ·
Replies
25
Views
2K