Capacitor Fundamentals & Circuit Laws

Capacitance is defined as the ability of a capacitor to store electrical charge.

The basic principle of Kirchhoff's Current Law states that the sum of all currents entering a circuit junction is equal to the sum of the currents leaving it.

Leakage / Self-Discharge: Although a fully charged capacitor should theoretically remain charged when disconnected from a power source, in practice, the voltage across it decreases over time. This phenomenon is known as leakage or self-discharge.
Charge Retention Variation: Different capacitors vary in how long they can hold their charge.
Discharge Example:
- When a capacitor, fully charged to a DC source voltage (e.g., 24 V), is disconnected, it initially retains that voltage.
- However, if this charged capacitor is then connected to a resistor (by closing a switch), it acts as a DC power source, supplying power to the resistor.
- Due to its limited stored charge, the capacitor quickly discharges, and its voltage drops to 0 V. Once fully discharged, no further current flows in the circuit.

Magnetism is defined as the property of a material to exert a force (either attraction or repulsion) on another material from a distance.

Capacitance (C):
- Definition: The primary characteristic of a DC capacitor, expressing its ability to store electrical charge.
- Relationship to Charge: A higher capacitance value indicates a greater amount of stored charge.
- Unit of Measurement: Measured in Farads (F), though commonly expressed in microfarads (\mu F) due to the large size of a Farad.
- Nomenclature: Named after English scientist Michael Faraday, who made significant contributions to electromagnetism and electrochemistry.
- Symbol: Denoted by the letter C.
Tolerance:
- Definition: Indicates the permissible variation of the capacitor's actual capacitance from its nominal (stated) value.
- Expression: Given as a percentage of the nominal capacitance.
- Precision: Tolerance can be