An electrical circuit diagram in which nine identical resistors of 3 Ω each are connected as shown. Ammeter A1 reads 1 ampere.
Generated by claude-sonnet-4-6 · 2026-06-15 06:44 · grounding stimulus
Model Answer
(a) A1 and A3 read the same value (1 A each), because they are in the same series branch of the main circuit. The current through a series path remains constant throughout.
(b) A2 reads half the reading of A3 (i.e., 0.5 A each in parallel branches), because two identical resistors are connected in parallel at that section, so current splits equally. Thus A2 = A3/2.
(c) The nine resistors (3 Ω each) are arranged so that three parallel combinations of three series resistors form the network.
- Each series branch: 3 × 3 = 9 Ω
- Three such branches in parallel: R_eq = 9/3 = 3 Ω
- Voltmeter reading: V = I × R = 1 × 3 = 3 V
Source: Chapter 11 – Electricity, Combination of Resistors (Series and Parallel)
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Explanation
- (a) A1 and A3 are on the main (series) line, so current is unchanged — same reading.
- (b) A2 is in one of two equal parallel branches, so it carries half the total current reaching that junction.
- (c) Examiners expect you to show the step-by-step equivalent resistance calculation before applying V = IR. Writing just the final answer without working may cost marks.