# Mutual Inductance (ouch, my brain)

1. Feb 27, 2007

### Dart82

1. The problem statement, all variables and given/known dataDuring a 65 ms interval, a change in the current in a primary coil occurs. This change leads to the appearance of a 6.0 mA current in a nearby secondary coil. The secondary coil is part of a circuit in which the resistance is 12 . The mutual inductance between the two coils is 3.1 mH. What is the magnitude of the change in the primary current?

2. Relevant equations
mutual inductance: M = (number of loops in coil 2 * flux through coil 2)/ current of coil 1

emf = -M x (change in voltage of coil 1/change in time)

3. The attempt at a solution
i could use faraday's law to solve for change in current of coil 1, but i dont know what the emf is.
i know the formula for emf is vBL, but i dont know v, B, or L!!!
i cant use the mutual inductance formula because i dont know the # of loops in coil 2.
If someone could please point me in the right direction here i would greatly appreciate it.
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution