Induced Current Direction in a Changing Magnetic Field

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The discussion centers on calculating the induced current in a 50-turn coil as the external magnetic field decreases from 1.8 T to 0 T over 3.3 seconds, with a coil resistance of 2.8 ohms. The induced current is calculated to be approximately 0.9442 A using the formula -N(B/t)*A. Participants emphasize the necessity of a changing magnetic field to induce current, referencing Faraday's Law. The direction of the current is debated, with options being counterclockwise (CCW) or clockwise (CW), depending on the orientation of the magnetic field. Understanding the relationship between changing magnetic fields and induced electromotive force (emf) is crucial for solving these types of problems.
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Homework Statement



The component of the external magnetic field along the central axis of a 50 turn coil of radius 5.7 cm decreases from 1.8 T to 0 T in 3.3 s.

(a) If the resistance of the coil is 2.8 ohm, what is the magnitude of the induced current in the coil?

(b) What is the direction of the current if the axial component of the field points towards the viewer?

1. CCW
2. CW

Homework Equations



EMF=-(phi)/(time)

Phi=BASin(theta)

The Attempt at a Solution


I found the current using -N(B/t)*A

I found it to be 0.9442 A.

Now I'm just not sure on part B.
 
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Well, there won't be any current unless the B is changing!
"A changing B causes an E to circulate around it."

Check out Faraday's Law in your textbook or Wikipedia.
 
B is changing, though. It said in the problem that "B decreases from 1.8T to 0T."
 
Yes, B is changing so you will get an emf in the coil, causing a current.
I meant that any formula you find for the emf MUST have a changing B.
Faraday's Law is what you are looking for.
 

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