Rate of Field Change for Induced Current of Loop

[tevatron1]

Homework Statement

A single conducting loop of wire has an area of 8.0×10−2 m^2 and a resistance of 110 Ω. Perpendicular to the plane of the loop is a magnetic field of strength 0.37 T.

At what rate (in T/s) must this field change if the induced current in the loop is to be 0.33 A?

Homework Equations

Trying to solve for ΔB/Δt

The Attempt at a Solution

We have a change in magnetic flux, but it seems to be due to ΔB rather than ΔA, so Δflux = ΔB*Acosθ (However since cos(90) = 0, I'm not sure if this will be correct).

Using Faraday's Law |ε| = N|(Δflux/Δt)|
Substituted Δflux = ΔB*A into Faraday's Law --> ε = N(ΔB*A/Δt)
Substituted the equation for the induced EMF into I = |ε|/R and solved for ΔB/Δt
ΔB/Δt = I*R/A (N=1 because the loop has 1 turn)

453.75 T/s = (.33A)*(110Ω)/(8.0*10^-2 m^2)
asks for 2 significant digits -> 450 T/s = Final Answer

I'm not sure where I'm going wrong...

 

[kushan]

Homework Statement

We have a change in magnetic flux, but it seems to be due to ΔB rather than ΔA, so Δflux = ΔB*Acosθ (However since cos(90) = 0, I'm not sure if this will be correct).
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θ would not be 90 as Area vector and B make 0 angle

 

[tevatron1]

θ would not be 90 as Area vector and B make 0 angle

Okay, then cos(0) = 1, which would prove that my assumption Δflux = ΔB*A*cos(0) = Δflux = ΔB*A

How does the rest of my thought process look?

 

[kushan]

as as i know you are doing correctly ,
where are you stuck ?

 

[tevatron1]

as as i know you are doing correctly ,
where are you stuck ?

Mastering Physics tells me this is the wrong answer, though it does not give any explanation as to why.

 

[kushan]

what is " mastering physics "

 

[tevatron1]

what is " mastering physics "

It's the online website for our physics homework. When you enter your answer, you are told whether or not your answer is correct. You are given 5 attempts, during which the points you earn diminish.

 

[kushan]

Even I am in confusion as they have given magnitude of magnetic field
(which means a constant field ) but asking find at what rate it would vary

 

[tevatron1]

Even I am in confusion as they have given magnitude of magnetic field
(which means a constant field ) but asking find at what rate it would vary

Yes, I noticed this as well. I purposely left that out of my equation as we are attempting to solve for ΔB/Δt. I assume it's the authors of the homework trying to trick us into thinking the value is necessary. Though I cannot see how it could be.

 

[kushan]

I am sorry as I fail to help you further with this problem

 

[technician]

You know the resistance of the loop and you know the current so you should be able to find the induced emf

 

[tevatron1]

"I am sorry as I fail to help you further with this problem "

Thanks, Kushan. I appreciate your help. I think there might be an issue with the website. It wouldn't be the first time.

Technician: You might notice that is exactly what I attempted to do... No worries though.

 

[tevatron1]

As it turns out, the website wanted a different number of significant figures. Albeit, an incorrect number with the given information...

 

[kushan]

Thank god