# Homework Help: Current produced by varying magnetic flux

1. Jun 29, 2011

### Tosh5457

I'm translating the problem, so sorry for the errors.

1. The problem statement, all variables and given/known data
Radius of the upper circumference = 5cm
Radius of the lower circumference = 9cm
Resistance/meter = 3.00 ohm/meter
B is the magnetic field: DB/dt = 2.00 T/s

What's the magnitude of the current, and where does the current points to?

2. Relevant equations

EMF = $-N \ \frac{\Delta \Phi_B}{\Delta t} \ \ \mbox{or} \ \ -N \ \frac{d\Phi_B }{dt}$
V = RI

3. The attempt at a solution

#### Attached Files:

• ###### figure20001.jpg
File size:
10.3 KB
Views:
112
Last edited: Jun 29, 2011
2. Jun 29, 2011

### WatermelonPig

Well, find the magnetic flux from the external field; the current should be produced in order to oppose an change in magnetic flux.