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We systematically studied the effect of current ripple on the determination of n-value, which is the index of the shape of the electric field-current (E-I) curve. Commercial Nb3 S n wires were measured with controlled amounts of ac ripple. Substitution- box, superconductor simulator circuits were also measured. A battery-powered current supply was used to provide the dc with ripple currents. The ripple frequencies were 60,120, and 360 Hz, to represent common electrical power harmonics in high-current power supplies. A previous study focused on the effect of ripple on the determination of dc critical current (Ic); the current study focuses on how ripple changes the n-value and shows that ripple has a larger effect on n-value than on Ic. We examined models and measurements on simulators to reproduce and explain the effects observed in measurements on superconductors. Current ripple and spikes may be sources of differences in n-values measured at different laboratories.