Determine Current in a Solenoid

[rmcgovern]

Homework Statement

As a new electrical technician, you are designing a large solenoid to produce a uniform 0.170 T magnetic field near the center of the solenoid. You have enough wire for 4200 circular turns. This solenoid must have a length of 1.10 m and a diameter of 1.50 cm. What current will you need to produce the necessary field?

Homework Equations

B=μ₀nI/2r at the center of a solenoid

The Attempt at a Solution

I have rearranged the equation to get I=B2r/μ₀n. I found the radius to be 7.5*10^-3 m (1/2 diameter) and n=4200 (# of turns). Plugging in the numbers I got a result of 0.483 A which is apparently incorrect. I am confused as to why the length of the solenoid was included in the problem description and am unclear as to where I may have gone wrong (having double checked the math). Does anyone have any suggestions?

 

[rmcgovern]

Nevermind, figured it out using flux.