Science (086) — AI-generated practice question

When three resistors are connected in parallel across a battery, the potential difference across each resistor is the same (equal to the terminal voltage of the battery). However, the current through each resistor is different.

The total current I drawn from the battery is equal to the sum of the currents through each individual branch:

$$\boxed{I = I_1 + I_2 + I_3}$$

where $I_1$, $I_2$, and $I_3$ are the currents through resistors $R_1$, $R_2$, and $R_3$ respectively.

This is because, at each junction, charge is conserved — the total charge flowing in per second equals the total charge flowing out. Hence, the total current splits among the parallel branches and recombines to give I.

Source: Chapter 11, Section 11.6.2 — Resistors in Parallel

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• The key relation examiners want is I = I₁ + I₂ + I₃ (Eq. 11.15 from the textbook). Always write it as a numbered/boxed expression.
• Briefly state why (conservation of charge / current splits at junction) — this earns the reasoning mark in a 3-mark question.
• Mention that the potential difference across each parallel branch is the same — this is the defining feature of parallel combination and often fetches 1 mark.
• Don't confuse this with the series rule (V = V₁ + V₂ + V₃); parallel → currents add, series → voltages add.