Electric Circuits: Parallel Resistors and Measurements

Vocabulary flashcards covering key terms and concepts from parallel resistors, measuring instruments, and circuit fundamentals.

Current (I)

The rate at which electric charge flows through a circuit; measured in amperes. In parallel circuits, the total current splits into branch currents.

Potential Difference (ΔV) / Voltage

The driving force that pushes charges through a circuit; in parallel circuits, the same voltage is across all components.

Resistance (R)

A property of a component that limits current for a given voltage; measured in ohms (Ω). R = V/I.

Ohm's Law

Fundamental relation V = I·R that connects voltage, current, and resistance in a circuit.

EMF (ε) / Battery

The ideal voltage supplied by a source; electromotive force of a battery.

Ammeter

Instrument for measuring current; has ideal zero resistance and is placed in series in a circuit.

Voltmeter

Instrument for measuring voltage; has ideal infinite resistance and is placed in parallel with the component.

Parallel Resistors

Configuration where components share the same two nodes, experience the same voltage, and have currents that add up.

Equivalent Resistance in Parallel (Req)

The single resistance that would draw the same total current as the parallel network; 1/Req = 1/R1 + 1/R2 + …; Req < any Ri.

Junction Law (Kirchhoff’s Current Law)

At a junction, the total current into the node equals the total current out: Iin = Iout (I = I1 + I2 + …).

Current Division

In a parallel circuit, the total current I splits into branch currents I1, I2, … such that I = I1 + I2 + …; each branch current is In = V/Rn.

Open Circuit

A path with infinite resistance where no current flows.

Short Circuit

A path with zero resistance (ideal conductor) that can cause very large currents; potentially dangerous.

Power (P)

Rate at which electrical energy is converted; P = V I = I^2 R = V^2 / R.

P = I^2 R

Power dissipated by a resistor equals the square of the current times the resistance.

P = V^2 / R

Power dissipated by a resistor equals the square of the voltage divided by the resistance.

Brightness and Power

Bulb brightness is related to the power dissipated; more power -> brighter.

Voltage Across Parallel Resistors

In a parallel circuit, the voltage across each resistor equals the source voltage (emf) because they are directly connected in parallel.

Identical Resistors in Parallel

If n identical resistors R are in parallel, the equivalent resistance is Req = R/n.

Ideal Conductor

A perfect conductor with zero resistance; wires are modeled as ideal conductors to connect components without voltage drop.