# Magnitude and direction of induced current with magnetic field

1. Feb 26, 2010

### skibum143

1. The problem statement, all variables and given/known data
A conducting rod whose length is 25 cm is placed on a U-shaped metal wire that has a resistance of 8 ohm. The wire and rod are placed in the plane of the paper. A constant magnetic field of strength 0.40 T is applied out of the paper. An applied force moves the rod to the left with a constant speed of 6.0 m/s. What is the magnitude and direction of the induced current in the wire?

2. Relevant equations
Fwire = iLB
I = V/R
F = qvB

3. The attempt at a solution
I don't understand how to solve for the current. Is there a relationship between velocity and something else here that can help me solve for it? I have the length (.25m) and B field (.40T), so if I knew current I could solve for F. I also don't know how to find q of the conducting rod.

The figure is attached. Thanks!

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2. Mar 1, 2010

### skibum143

Can anyone help me with this problem? Thanks!

3. Mar 1, 2010

### Mindscrape

Do you know faraday's law? Remember that flux is [itex]\int \int B \cdot da[/tex]. The negative time derivative of flux will give you EMF (or voltage).