Inductance & magnetic flux problem -

[bcjochim07]

Inductance & magnetic flux problem -- please help

Homework Statement

The magnetic field of a place on Earth has strength 55 microTesla and is tilted 60 degrees below horizontal. A 200 turn coil with diameter 4cm and resistance 2 ohms is connected to a 1 microFarad capacitor. The coil is held in a horizontal plane and the capacitor is discharged. Then quickly the coil is rotated 180 degrees. Afterwards, what is the voltage on the capacitor?

Homework Equations

The Attempt at a Solution

I have the flux through the coil initially:

= pi* (.02)^2 * (5.5e-5) * cos (30) * 200 = 1.2 e -5 Wb

But I really don't understand what happens when the capacitor discharges. Also, how does just flipping the loop over will change the flux to induce a current? It seems to me that the angle doesn't change or anything. Please help.

 

[bcjochim07]

Any ideas? This is really bugging me that I don't understand this very well.

 

[bcjochim07]

hmmm... ok
So I guessed that the flux would be the same when flipped only with the opposite sign:

(1.2e-5)--(1.2e-5) = change in flux = 2.4 e-5 Wb

(2.4e-5)/dt = EMF

(2.4e-5)/(2ohm)dt = dq/dt

dq= 1.2 e-5 C = (1e-6F)Vc
Vc = 12 V

I do have another question though. The capacitor would discharge again after being rotated, right?