# Faraday's vs Ampere's Laws and current density

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

tech99
Gold Member
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