1. The problem statement, all variables and given/known data A single phase transformer circuit is assembled with an RC load. A voltmeter is connected to across the capacitor and an ammeter in series with the primary. The output of the ammeter is connected to the X-channel of an oscilloscope and the output of the voltmeter is connected to the Y-channel. The oscilloscope is set to X-Y mode and the resulting display is a Lissajous figure that closely resembles the B-H hysteresis loop. Explain why this is the case... 2. Relevant equations N/A 3. The attempt at a solution The current in the primary is the current that establishes the flux in the core i.e. provides the magnetomotive force which effectively represents the behavior of the H field. Since the e.m.f. produced by the transformer windings is proportional to the rate of change of flux the voltage lags the flux by 90deg. Lissajous figures represent phase differences between two signals. In this case the frequency of the two signals is the same but anti-phase. If the current was perfectly sinusoidal the figure would be an ellipse however due to saturation effects the current is not perfectly sinusoidal which is observed by the resulting Lissajous figure. I think this answer is on the right lines however I'm confused as to why the need for an RC load? Also, the magnetising current should be more prominent under no load however in this there is a 150kohm and 2microF capacitor which represents some load impedance on the transformer.