How Can I Use Magnetic Field Protractor to Solve for Magnetic Flux?

[Silverado]

Homework Statement

[/B]

Homework Equations

R = ρ (l/A)
I = ε/R
s = rθ
Magnetic flux = Integral(B ⋅ dA)

The Attempt at a Solution

[/B]
I managed to solve parts (a) and (b) independently. Here is my work for those two parts:

My real issue is with part (c) which uses the answers from (a) and (b). I have absolutely know idea how to solve part c, except that it involves in some way the formula Magnetic flux = Integral(B ⋅ dA)

 

[TSny]

Be careful with converting mm² to m².

So far, you have not mentioned the basic law of electromagnetism that accounts for the induced current in the circuit.

 

[Silverado]

Be careful with converting mm² to m².

So far, you have not mentioned the basic law of electromagnetism that accounts for the induced current in the circuit.

Yes, You're right. That law goes as follows:

ε = - the rate of change of flux (sorry I do not know how to write this in the proper notation)

And the induced current is found, simply, through Ohm's law: ε = iR

So how can I, with this, go about part (c)?

 

[TSny]

ε = - the rate of change of flux

How do you find the rate of change of a quantity. What mathematical operation is involved?

 

[Silverado]

How do you find the rate of change of a quantity. What mathematical operation is involved?

Take the derivative. So I can take the derivative of part (b). But theta needs to be expressed in terms of the time, t?

 

[TSny]

Yes.

 

[Silverado]

Yes.

Thank you!