Flux through a coil due to Self-Inductance

[betamu]

Homework Statement

A coil has 460 turns and self-inductance 7.50 mH. The current in the coil varies with time according to i=(680mA)cos[πt/(0.0250s)].

What is the maximum average flux through each turn of the coil?

Homework Equations

$\varepsilon_{ind} = N \frac{d\Phi}{dt} , \varepsilon_{ind} = L \frac{di}{dt}$

The Attempt at a Solution

I set the above equations equal to find $N \frac{d\Phi}{dt} = L \frac{di}{dt}$ and integrated both sides wrt t to find $N\phi = Li$, input the given equation for i with the entire cos() portion = 1, as it is asking for the maximum average flux, set $N = 460$ and solved for $\Phi = 1.11*10^{-5}$ but this doesn't seem to be the correct answer.
Is it the "average" flux bit that's throwing me off?

 

[Delta2]

The average flux is zero, the maximum flux is as you say. But we need to understand what exactly we mean by the term "maximum average" flux.

Can you provide the exact statement of the problem (perhaps via a screenshot from the book , or from the page of the e-document)?.

 

[betamu]

Attached is a screenshot of the problem. It asks for the "maximum average flux" through each turn of the coil. I was thinking the average would be zero, but MP didn't accept that as an answer, either.

I'm confused as to what the problem means by "maximum average." Is it asking for the average of all of the "positive" values of flux?

edit: Sorry, I'm not sure why I can't upload it in higher resolution. I saved it much higher resolution than it appears on the forum - does PhysicsForums downsize?

 

[Delta2]

The screenshot is OK.

I am also confused about what it means by maximum average. Maybe it asks for $\frac{1}{T}\int_0^T|\Phi(t)|dt$ where T is the period (inverse of frequency) of the flux (or of the current).

 

[betamu]

Hm, okay. It wouldn't be solvable with the given information in that case, right?

I'll email my professor about it and hope I get something back.

 

[Delta2]

It is solvable, the period is given, you can find it from the given term inside cos() that is the $\frac{\pi t}{0.0250}$

 

[betamu]

Thanks for the help the other day. Sorry to get back to this thread so late.

My initial answer was correct - I wasn't paying attention to the units used for the answer which were already given by the problem. I had the correct answer, but to the wrong power of 10.