A student conducted an experiment where they made an electromagnet. They used a battery that was 10V, but changed the varying number of turns around the nail. Then the student tested how many pins it attracted. They recorded their data in the table below.
Number of turns, N Number of pins attracted
20 9
30 14
40 18
50 22
60 27
Based on the investigation the student completed, what would be the best conclusion for this student's work?