4-True-False (experiment 6) : a) 1/(f^2) vs output current is a straight line ( f is frequency) b) Magnetic field of Helmholtz coil and earth are constant during the experiment. c) The sign of B_axial in experiment 6.2 can change the results for the value of N. d) In an ideal selenoid, the sign of B_radial is independent of sign of B_axial e) In experiment 6.1, If we use a magnetic dipole with parameters 4m and 2I, the intercept of 1/(T^2) vs current stays the same since the magnetic field of earth is constant.