# Homework Help: A 2cm diameter cylindrical solenoid of 10 loops and 20cm long

1. Dec 10, 2011

### Physics8o8

1. The problem statement, all variables and given/known data

A 2cm diameter cylindrical solenoid of 10 loops and 20cm long is in a perpendicular magnetic field of 0.7Tesla directed away from you. The field increases to 2.7Tesla in 100ms. The loop has 8Ω.
What is the EMF?
What is the current?
What is the magnetic field of the center of the current?
What is the self inductance of the solenoid?

2. Relevant equations

Don't know where to start? Do I use the Bfield that the solenoid is in or the ΔB? When I used B with the eq: I=2radius / μN , I got an extreme current.

3. The attempt at a solution

Am I using the right equations?
eq: B = μNI / 2 radidus
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Dec 10, 2011

### Liquidxlax

Re: Emf

how do you find flux?

well flux is

$\Phi$=∫B*dA

emf is the time rate of change of the magnetic field

EMF= -$\frac{d\Phi}{dt}$

which in your case would be -(B2-B1)/t

To find the B field inside a solenoid you are going to need to do an amperian loop

to find i think B=μoNI/L

that should be enough to find what you need

3. Dec 11, 2011

### Physics8o8

Re: Emf

Thank you ..... $\Phi$=∫B*dA... This equation helped a lot.