Faraday's law of electromagnetic induction

[acidandroid]

Homework Statement

A flat circular coil with 139 turns, a radius of 5.74 x 10-2 m, and a resistance of 0.502 Ω is exposed to an external magnetic field that is directed perpendicular to the plane of the coil. The magnitude of the external magnetic field is changing at a rate of ΔB/Δt = 0.952 T/s, thereby inducing a current in the coil. Find the magnitude of the magnetic field at the center of the coil that is produced by the induced current.

Homework Equations

Faraday's Law of Electromagnetic induction:
emf = -N(delta feta/delta time)

The Attempt at a Solution

I calculated the emf according to the Faraday's Law of Electromagnetic induction as 1.3696 V. But I do not know how to derive the magnetic field at the center of the coil, and I do not understand why resistance is given in this problem.

Please help!

 

[G01]

Homework Statement

A flat circular coil with 139 turns, a radius of 5.74 x 10-2 m, and a resistance of 0.502 Ω is exposed to an external magnetic field that is directed perpendicular to the plane of the coil. The magnitude of the external magnetic field is changing at a rate of ΔB/Δt = 0.952 T/s, thereby inducing a current in the coil. Find the magnitude of the magnetic field at the center of the coil that is produced by the induced current.

Homework Equations

Faraday's Law of Electromagnetic induction:
emf = -N(delta feta/delta time)

The Attempt at a Solution

I calculated the emf according to the Faraday's Law of Electromagnetic induction as 1.3696 V. But I do not know how to derive the magnetic field at the center of the coil, and I do not understand why resistance is given in this problem.

Please help!

The emf plus the resistance in the wire produce a finite current that you can calculate, right?

Does this current produce a magnetic field?

 

[acidandroid]

So I did I=E/R to calculate current, then used B=(4pi*10^-7)*I/2*pi*r to get magnetic field but still it's different from the answer. :( I'm just stuck.

The emf plus the resistance in the wire produce a finite current that you can calculate, right?

Does this current produce a magnetic field?

 

[G01]

So I did I=E/R to calculate current, then used B=(4pi*10^-7)*I/2*pi*r to get magnetic field but still it's different from the answer. :( I'm just stuck.

That's the right idea.

I can't help find a mistake if I can't see your work. Please post your calculation.

 

[acidandroid]

Okay so...

emf= -N A cos 0 (change in B/change in t)
=-139 turns*(0.01035 m^2)*1*(0.952 T/S)
=-1.3696 V

I=E/R
=-1.3696 V/ 0.502 ohm
=-2.728

B=N*(4pi*10^-7)*I/2R
-this is the equation for the magnitude of the magnetic field at the center of a flat circular loop consisting of N turns, each of radius R.
=139*(4pi*10^-7)*-2.728/2*(5.74*10^-2)
=-.00415 TStill a wrong answer. I don't know where to go from here.

That's the right idea.

I can't help find a mistake if I can't see your work. Please post your calculation.

 

[G01]

Your work seems fine to me. How do you know the answer is wrong?