# Properties of Generator

1. Oct 28, 2008

### haxxorboi

1. The problem statement, all variables and given/known data
The conducting coil rotates around the axis of rotation in the direction of the right-hand rule (thumb pointing along the axis of rotation, the fingers curl in the direction of rotation). A uniform magnetic field B points from left to right. The "flux" refers to the magnetic field flux through the coil; define the direction of positive flux as flux from the red side to the blue side.

All questions are T/F

1. In B the flux through the coil is zero and increasing.
2. In A the flux through the coil is zero and decreasing.
3. In B the flux through the coil has the maximum positive value.
4. In A the emf around the coil has the maximum value.
5. In A the emf around the coil is zero.
6. In C the magnitude of the emf around the coil has the maximum value.
7. In A the flux through the coil has the maximum positive value.
8. In A the flux through the coil has the maximum negative value.

2. Relevant equations
EMF=delta magnetic flux/delta time
Flux=B*A*cos(theta)

3. The attempt at a solution
1. F, All flux through coil which will decrease
2. F, No flux through coil which will increase
3. T, All flux through coil which would make this a maximum point in flux graph
4. F, No flux = no EMF
5. T, Same reasoning as 4, except opposite answer
6. F, Again no flux means no EMF
7. F, No flux through coil in C
8. F, Zero flux is halfway to being the max negative flux, which would be position "D"

Can someone tell me what I'm messing up here. I'm obviously mixing something up here.

Thanks

2. Oct 28, 2008

### haxxorboi

Ok, upon further thinking I've discovered in this case that...
Flux=sin(x)
EMF=-cos(x)

1. In B the flux through the coil is zero and increasing.
2. In A the flux through the coil is zero and decreasing.
3. In B the flux through the coil has the maximum positive value.
4. In A the emf around the coil has the maximum value.
5. In A the emf around the coil is zero.
6. In C the magnitude of the emf around the coil has the maximum value.
7. In A the flux through the coil has the maximum positive value.
8. In A the flux through the coil has the maximum negative value.

Thus,
1. F, flux is at a max and decreasing
2. F, flux is zero and increasing
3. T, flux at max
4. F, EMF is at minimum here
5. F, Again, it's minimum here
6. T, EMF at max here
7. F, flux at zero here
8. F, flux at zero here

This is hurting my head. Am I missing something huge here or what?

3. Oct 29, 2008

### haxxorboi

Anyone? I'm struggling here bad...

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