Current and Capacitor in AC Circuit Apparatus

The “Capacitance in Series and Parallel in an AC Circuit” science kit by IBEX Sciences is an educational laboratory apparatus designed for school and college students to study the behavior of alternating current (AC) passing through capacitors. This working model enables experiments analyzing how current, voltage, frequency, and capacitance relate to each other.

The apparatus allows students to practically verify Ohm’s Law for AC circuits containing pure capacitance. By varying capacitors or tracking the signal, users study the fundamental characteristics of capacitive reactance:

The Current-Capacitance Relationship: Verifying that at a fixed frequency, the AC current (I) is directly proportional to the capacitance (C), keeping the ratio I/C constant.

Capacitive Reactance: Observing how the opposition to AC current decreases as either capacitance or supply frequency increases

Phase Relationship: Demonstrating how alternating voltage charges and discharges the plates continuously, causing the current to lead the voltage by 90° (or 1/4 cycle).

While the specific layout is integrated into a unified project board by IBEX Sciences, an experimental setup of this type typically comprises:

• Step-Down Transformer: Safely reduces the mains voltage down to a low-voltage AC supply (typically 12V AC).
• Capacitor Bank: A selection of multiple distinct capacitors (often ranging from 10μF to 50μF) that can be switched into the circuit individually, in series, or in parallel.
• A.C. Milliammeter & Voltmeter: Integrated analog or digital meters to accurately track the RMS current flowing through the loop and the voltage across the components.
• Connecting Sockets/Clips: Facilitates clean circuit modifications without soldering.