The experimental components were faulty. A functional resistor and inductor would produce identical results to the simulation.

The discrepancy is only due to the oscilloscope’s limited sampling rate. If a faster, higher-resolution oscilloscope was used, the experimental spike would more accurately match the ideal simulation.

The “spike” is just an artifact of the non-ideal square wave function generator, and is not related to the circuit or oscilloscope. This experiment has simply demonstrated the non-idealities present in the signal generator.

The oscilloscope has a finite bandwidth, the signal generator has a non-zero rise time, and the circuit components have non-ideal parasitic capacitances and resistances. These factors prevent the measurement of a perfectly sharp spike, resulting in a more rounded, lower amplitude waveform.

The oscilloscope’s probes introduce a significant amount of parasitic capacitance (approx. 8pF), which resonated with the circuit’s inductance, causing the spike to be smaller and rounded.

The simulation is less accurate than theory. The discrepancy is because the simulation software only has a finite precision and cannot model the near infinite values predicted by theory.