# Magnetic field inside a sperical coil

1. Jun 13, 2010

1. The problem statement, all variables and given/known data
What is the induction in the centre of a spherical coil with N turns, the current I and the radius R?

2. Relevant equations
Biot-Savart law $$\mathbf{B} = \int\frac{\mu_0}{4\pi} \frac{I d\mathbf{l} \times \mathbf{\hat r}}{|r|^2}$$

3. The attempt at a solution
I know what the induction from one turn is but I don't have a clue how to sum these up. And as have to have this homework done by Tuesday I'll be most grateful for any help.

2. Jun 13, 2010

### zzzoak

In Biot-Savart law you may change
I to NI.