# Where did I go wrong?

1. Nov 3, 2005

### lw11011

A solenoid 77.1 cm long has 340 turns and a radius of 1.92 cm. If it carries a current of 1.85 A, find the magnetic field along the axis at its center. Answer in units of T.
I know the formula for the magnetic field is:
Magnetic field = permeability x turn density x current
I entered -
B=(1.25664x10^-6)(340/.771)(1.85)
Where did I go wrong?

2. Nov 3, 2005

### ranger

I think you could use this

$$B = \frac{\mu_0.I.N}{l}$$

Last edited: Nov 3, 2005
3. Nov 3, 2005

### cepheid

Staff Emeritus
:tongue2: He DID use that formula. You just reproduced what he said in words using symbols.

4. Nov 3, 2005

### cepheid

Staff Emeritus
Looks ok so far. What makes you think that you went wrong? You didn't even post an answer, so it is not at all clear from your post what the problem is.

5. Nov 3, 2005

### ranger

I stand corrected

6. Nov 3, 2005

### lw11011

By using that formula I got the answer, 0.001 T. The computer program for our homework said the answer was wrong.