The discrepancy is due to parasitic capacitance in the inductor. This capacitance shifts the resonant frequency higher, which is the cause of the reduced attenuation.

The inductor’s DC winding resistance improves the filter performance, so the experimental result should have been sharper than simulation.

The theory is correct. The experiment likely failed due to measurement error and can be ignored. The theoretical/simulated value (-50dB) is the correct value.

The simulation is flawed. Ideal component models are too complex and introduce precision / rounding errors. The experimental result (-20dB) is closer to the true ideal value.

The experimental components must have been incorrect due to tolerances, manufacturing defects, etc.

The DC winding resistance of the inductor lowers the Q factor. This highlights the importance of theory, simulation, and experimental phases; theory provides an ideal goal, simulation (when accounting for real-world effects such as can predict real behaviour, and experimentation validates the practicality of the design.

The discrepancy is due to the inductor’s winding resistance, . This resistance increases the Q factor of the circuit, making the filter too sharp for the oscilloscope to measure, which is why it appears to be -20dB.

A high Q requires imaginary numbers, and because they are imaginary, such circuits are not real.

A selective filter requires a high Q, which corresponds to a narrow bandwidth. In a series RLC circuit, Q is inversely proportional to R. Therefore, R should be minimised for high selectivity.

A high Q factor leads to a wide bandwidth, which is ideal for filtering. Q is maximised by setting L = C, as R has no effect on Q, only on the resonant frequency.

A high Q factor is desirable for a selective filter and can be implemented by maximising the resistance R. A high Q results in a wide bandwidth.

The Q factor is defined as the ratio of bandwidth to resonant frequency ( Q = BW / ). A selective filter requires a low Q, which is achieved with a low resistance R.

The Q factor is defined as Q = /BW. A high Q (i.e., narrow bandwidth) is achieved by increasing R, since the resonant frequency is directly proportional to R.

The bandwidth is independent of Q factor and is only set by R. The Q factor is set only by L and C. A selective filter should have a low R, and a high .

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.

The capacitor voltage is gradual as it opposes instantaneous change in current

The capacitor voltage is spiky as it opposes instantaneous change in current

The inductor voltage is spiky as it opposes instantaneous change in current

The inductor voltage is spiky as it opposes instantaneous change in voltage

The inductor voltage becomes non-physical