Magnetic feild in circular coil

[goWlfpack]

Homework Statement

A 20 turn circular coil of length 5.9 cm produces a magnetic field of magnitude 1.9 mT at its center. Find the current in the loop

Homework Equations

B=(moconstant)nI
where n is the number of turns per unit length and I is current. magnetic field is B

The Attempt at a Solution

so i put in .0019 T for B
i put in .059 m and divided 20 by that to find the turns per unit or m
i plugged them in with the constant and got a red x... any suggestions?

 

[Defennder]

Your equation isn't correct to begin with. What about the length of the coil?