PHY2 – Resistors and Resistor Combinations, Part 1

Flashcards cover definitions, formulas, and conceptual applications related to series and parallel resistor networks, as presented in the Physics 2 lesson 8.4.1.

What characterizes a SERIES connection in an electric circuit?

All elements lie on a single path; the same current flows through every component.

In a series circuit, how are the individual voltages related to the total voltage supplied by the battery?

They add: V = V₁ + V₂ + V₃ + …

Write the formula for equivalent resistance in a series circuit containing R₁, R₂ and R₃.

R_eq = R₁ + R₂ + R₃

State the current relation for a series circuit.

I = I₁ = I₂ = I₃ = … (current is the same everywhere).

What distinguishes a PARALLEL connection from a series connection?

Branches share common terminal points; the voltage across each branch is the same, while the current splits among branches.

Give the voltage relation for any branch in a parallel circuit.

V = V₁ = V₂ = V₃ (same voltage across every branch).

Express the equivalent resistance for three resistors in parallel.

1/R_eq = 1/R₁ + 1/R₂ + 1/R₃

State the current relation at a junction in a parallel circuit.

I = I₁ + I₂ + I₃ (sum of branch currents equals total current).

What happens to total circuit resistance when an additional branch is added in parallel?

Equivalent resistance decreases, drawing more current from the source.

Why are household and building wirings arranged mostly in parallel?

A break or failure in one branch does not stop current in other branches; devices operate independently.

If a switch is closed so that an identical bulb B is added in parallel to bulb A, how does bulb A’s brightness change?

It does not change; voltage across A remains the same, so its current and brightness stay constant.

Using conservation of charge, explain current splitting at a junction.

The current entering a junction equals the total current leaving it (Iin = ΣIout).

Conceptual Example 1: Are the three diagrams in Hewitt’s Figure 5 equivalent? Why?

Yes; each path connects directly across the battery, so all three are parallel circuits.

Conceptual Example 2: Identical bulbs in parallel with an ammeter at points A, B, C. Rank current readings.

A = B = C (each branch draws identical current).

Conceptual Example 3: Identical bulbs in series with a voltmeter across one bulb. Rank voltage readings for diagrams A, B, C.

A (largest) > B > C; the single bulb in A gets full battery voltage, while B gets half and C one-third.

Give two conservation principles used to derive series and parallel rules.

Conservation of charge (current) and conservation of energy (voltage drops sum to battery voltage).

State Ohm’s Law as used in the lesson.

V = IR, where V is potential difference, I current, and R resistance.

Why does a break in one branch of a parallel circuit not stop current in other branches?

Because each branch provides an independent path connected directly across the same voltage source.