We have two long solenoids. One has radius R, length L, and N number of turns. The second one has half the radius, half the length but twice the number of turns. How does the magnetic field at the center of the two solenoids compare. Hint: Label solenoids and their characteristics with subscript. Write the equation for the magnetic field. Then divide to find the ratio. Possibly useful formula: o = 1.26 x 10-6, straight wire B = HONI 2R' Coil B = HONI 2 R Solenoid B = HONI L