# Homework Help: Find induced emf (among other things) in this current + motion

1. Oct 30, 2012

### 1MileCrash

1. The problem statement, all variables and given/known data

Attached

2. Relevant equations

3. The attempt at a solution

First, I thought that maybe the magnetic field's non uniformity didn't matter since the rate of change of flux was going to be the rate of change of area, but that's wrong.

So I thought I should do some kind of integral to figure out the magnetic field from the top to bottom "per unit area" but that doesn't even make sense.

So then I decided to find the magnetic flux by integrating B dA but that still doesn't make much sense to me.

What do I do?

And what does resistance have to do with it? Or is that for one of the lower questions?

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2. Oct 30, 2012

### 1MileCrash

In the integral for B dA, can I write the equation for B (mu 0 * i / 2piR) and replace R with the area for that R and integrate? Does that work?

3. Oct 30, 2012

### 1MileCrash

But that still won't get me a function of t so that I can differentiate to find rate... and R is constant anyway.

Very confused now.

4. Oct 30, 2012

### 1MileCrash

Is it some kind of double integral?