Circuit Diagrams, Kirchhoff's Laws, and Series/Parallel Circuits (Vocabulary Flashcards)

Vocabulary flashcards covering circuit diagrams, component symbols, Kirchhoff’s laws, series vs parallel circuits, voltage/current concepts, and key relationships like R_eq and Ohm’s law.

Circuit diagram

A simplified schematic using standard symbols to show how components are connected, not the messy real layout.

emf (E)

The electromotive force; the voltage provided by a battery to push current around the circuit.

Resistor (R)

A component with resistance R that limits current in a circuit.

Capacitor (C)

A component that stores electric energy, characterized by its capacitance C.

Ohm's Law

Relationship V = IR (or I = V/R); describes how voltage, current, and resistance relate in a circuit.

Kirchhoff’s Junction Law (Current Law)

At any junction, the sum of currents entering equals the sum leaving (conservation of charge).

Kirchhoff’s Loop Law (Voltage Law)

Around any closed loop, the sum of voltage gains and drops equals zero (conservation of energy).

Potential difference

The change in electric potential between two points; positive when moving to higher potential.

Voltage change across a battery (sign convention)

Passing from negative to positive terminal gives +E; passing from positive to negative gives -E.

Voltage drop across a resistor

As charges move through a resistor, their potential decreases by IR (ΔV_R = -IR).

Series circuit

Components connected end-to-end; same current flows through all; total resistance is the sum of individual resistances.

Parallel circuit

Components connected across the same two nodes; each experiences the full supply voltage; currents split among branches.

Equivalent resistance in series

R_eq = R1 + R2 + … (the resistances add in series).

Equivalent resistance in parallel

1/R_eq = 1/R1 + 1/R2 + … (reciprocal of total resistance).

Current in series

The same current flows through every component in a series circuit.

Voltage distribution in series

The total voltage is divided among components; larger resistance tends to take a larger share of the voltage.

Voltage across parallel branches

Each branch sees the full battery voltage V = E in an ideal parallel circuit.

Current distribution in parallel

The total battery current equals the sum of branch currents: Ibat = I1 + I2 + …; each Ii = V/R_i.

Brightness in series vs parallel (identical components)

Series: identical current through all; brightness can be equal if resistances are equal. Parallel: each branch has full voltage, brightness depends on each branch's resistance; identical branches have equal brightness.

Common misconception about batteries

A battery provides a fixed voltage, not a fixed current—the current depends on total circuit resistance.

Rule of thumb for loops

Draw the circuit, choose a current direction, walk the loop, and apply ΔV gains/drops to satisfy the loop equation (sum = 0).

Example intuition (simple loop)

With one battery and one resistor, the loop equation yields I = E/R, showing how the battery sets voltage and the resistor sets current.