# Finding induced emf, number of turns, and flux linkage of coil wound around solenoid

1. Apr 4, 2012

### kdawg4

A 30mH solenoid inductor is wound on a form 0.4 m in length and 0.1 m in diameter. A coil is tightly wound around the solenoid at its center. the coil resistance is 5.0 ohms. The mutual inductance of the coil and solenoid is 60μH. At a given instant, the current in the solenoid is 0.3A and is decreasing at a rate of 2.5A/s.

a) Find the number of turns in the winding of the solenoid
b) Find the induced emf at the given instant.
c) At the given instant, the flux linkage N(phi) for the solenoid is...

Hey guys, really need a nice simple answer here, thank you...I'm new to the forum by the way :D

At first I used the formula mu(n1)(n2)A/L equals the mutual inductance but now Im stumped since you have 2 unknowns and I don't know how to find one of them

Last edited: Apr 4, 2012
2. Apr 4, 2012

### Staff: Mentor

Re: Finding induced emf, number of turns, and flux linkage of coil wound around solen

Hi kdawg4, Welcome to Physics Forums.

Which part of the problem are you working on? Do you know the formula for the inductance of a solenoid?

3. Apr 4, 2012

### kdawg4

Re: Finding induced emf, number of turns, and flux linkage of coil wound around solen

I am currently workingon all three, and yes I know the formula for the inductance of a solenoid

4. Apr 4, 2012

### Staff: Mentor

Re: Finding induced emf, number of turns, and flux linkage of coil wound around solen

Okay then, for part (a), what values in the formula for the inductance of the solenoid are unknowns (values that you haven't been given)?