Topology swap thought experiment — starting with a classic RC integrator (series resistor feeding a capacitor to ground, output across the capacitor), if the positions of the components are swapped (series capacitor feeding a resistor to ground, output across the resistor), what does the new circuit implement?

Introduction / Context:
First-order RC networks can be arranged to emphasize integration (slow change) or differentiation (edge emphasis). An “RC integrator” typically has a series resistor and a shunt capacitor with the output taken across the capacitor. Swapping the positions of R and C and taking the output across the resistor yields the complementary high-pass behavior associated with an RC differentiator.

Given Data / Assumptions:

• Original circuit: series R, capacitor to ground, output across C.
• Modified circuit: series C, resistor to ground, output across R.
• High-impedance measurement so loading is negligible; small-signal linear behavior.

Concept / Approach:
In the differentiator arrangement (series C, shunt R, output across R), the capacitor passes rapid changes (high-pass action) while the resistor converts the changing current to a voltage. The output magnitude is therefore proportional to the rate of change of the input within the useful bandwidth, producing edge spikes to steps/pulses. Conversely, the integrator (series R, shunt C, output across C) accumulates charge and emphasizes low-frequency content (low-pass action).

Step-by-Step Solution:

Verification / Alternative check:
Frequency response: integrator has gain ∝ 1/ω at high frequencies (low-pass), while differentiator has gain ∝ ω at low frequencies (high-pass within limits). Swapping elements flips the response class.

Why Other Options Are Wrong:

• RL differentiator / RL integrator: incorrect component family.
• RC integrator: describes the original, not the swapped configuration.
• “Pure attenuator only”: while both topologies can attenuate, the key function here is differentiation.

Common Pitfalls:
Confusing where the output is taken; with RC differentiator it must be across the resistor, not the capacitor.

Final Answer:
RC differentiator.