Time Constant of RC Circuit - Physics Demonstrations - Time Constant of RC Circuit | Physics Undergraduate Labs

Purpose

Visualizes exponential charging and discharging of a capacitor driven by a square wave. Students observe the characteristic RC exponential curves on an oscilloscope and see how $\tau = RC$ governs the response time.

Agilent digital oscilloscope displaying square wave input and exponential RC response, Agilent function generator set to 3 kHz, and breadboard RC circuit on a gray module

Close-up of breadboard module with resistor array, electrolytic capacitor, and wiring to colored binding posts. Handwritten label reads "330 ohms" and "0.10 μs"

Oscilloscope close-up showing two traces: square wave input (top) and capacitor voltage with exponential rise and fall (bottom), displaying a full charge/discharge cycle

Figure 1: Complete setup: oscilloscope shows the input square wave (upper trace) and capacitor voltage with exponential charging/discharging (lower trace), with function generator and breadboard RC circuit.

Figure 2: The RC circuit breadboard with resistor and capacitor. Handwritten label indicates R = 330 Ω and τ ≈ 0.10 μs.

Figure 3: Close-up of oscilloscope traces showing the input square wave and the capacitor voltage with characteristic exponential charging and discharging curves.