Faraday's Law question

  • #1
101
0

Homework Statement


A circular loop of radius r = 12cm is in a uniform magnetic field B=.5T w/ its plane normal to the direction of the field. If the magnitude of B then decreases at a constant rate of -.01T/s, at rate should r increase so the induced emf in the loop is zero?


Homework Equations


Faraday's Law


The Attempt at a Solution


The question gives the initial emf in the loop = .01V and you can solve for the initial flux =.0023Wb. From here I don't know what to do.
 

Answers and Replies

  • #2
G01
Homework Helper
Gold Member
2,665
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If both the radius and the field are changing, what is the formula for the induced emf?

HINT:

You should have two terms in your equation, one involving the rate of change of B and one involving the change in r. You then want to pick a value for the rate of change of r such that both terms cancel.
 

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