Chapter 23 Circuits - Capacitors and Related Concepts

Vocabulary flashcards covering key terms and concepts from Chapter 23: Circuits, including voltmeters/ammeter usage, Kirchhoff laws, resistors, and capacitor networks (series/parallel) and RC dynamics.

Voltmeter

Instrument that measures the voltage (potential difference) across a component; designed with high input impedance to avoid drawing significant current.

Ammeter

Instrument that measures current in a circuit; placed in series; ideally has zero resistance to minimize voltage drop.

Kirchhoff's Junction Rule

At any circuit node, the algebraic sum of currents entering equals the sum leaving (charge conservation).

Kirchhoff's Loop Rule

The sum of voltages around a closed loop is zero (energy conservation).

Series Resistance

Resistors connected end-to-end; equivalent resistance is the sum R_eq = R1 + R2 + …; same current through each.

Parallel Resistance

Resistors connected across the same two nodes; voltages are equal; reciprocal of equivalent resistance is the sum of reciprocals: 1/R_eq = 1/R1 + 1/R2 + ….

RC Circuit

A circuit with a resistor and a capacitor; exhibits charging/discharging behavior with time constant τ = RC.

Time Constant

τ = RC; the characteristic time for charging/discharging; after about 5τ the response is effectively complete.

Capacitance (C)

Property of a capacitor; charge stored per unit voltage; Q = C·ΔV; units: Farads.

Capacitors in Parallel (Ceq)

Equivalent capacitance in parallel: Ceq = C1 + C2 + …; all capacitors share the same voltage.

Capacitors in Series (Ceq)

Equivalent capacitance in series: Ceq = 1/(1/C1 + 1/C2 + …); same charge flows through each capacitor.

Charge on a Capacitor

Stored charge is Q = C·ΔV; magnitude of charge relates to the capacitor’s capacitance and the voltage across it.

Charge Distribution in Parallel

Total charge in a parallel network is the sum of individual charges; each capacitor has the same voltage ΔV.

Charge Distribution in Series

In series, all capacitors carry the same magnitude of charge Q.

Equivalent Capacitor

A single capacitor that reproduces the voltage–current behavior of a network of capacitors.

Final Voltage on a Charging Capacitor

After connection to a battery, the capacitor voltage approaches the source emf ε (ideal conditions).

Voltage Across Capacitors in Series

In a series chain, ΔVi = Q/Ci for each capacitor; total ΔVC = Σ ΔVi.

Voltage Across Capacitors in Parallel

In parallel, ΔV is the same across all capacitors (equal to the supply voltage if directly connected).

Parallel vs Series Ceq Quick Tests

For parallel, Ceq > any individual C; for series, Ceq < any individual C.

Charging Exponential Formula

Vc(t) = ε(1 − e^(−t/RC)) for a charging capacitor.

Discharging Exponential Formula

Vc(t) = ε e^(−t/RC) when the capacitor discharges with no source.

Same Charge in Series

In a series network of capacitors, all capacitors carry the same charge magnitude Q.