O Levels Physics (5054)•5054/11/M/J/23
Explanation
Parallel cells extend battery life Steps:
- Assume diagram shows three 1.5V cells connected in parallel, as total e.m.f. remains 1.5V.
- In parallel, voltage equals single cell (1.5V), but internal resistance decreases to one-third.
- Total capacity (ampere-hours) triples compared to one cell.
- For same load current, discharge time extends proportionally to capacity.
Why A is correct:
- Parallel connection sums charge capacities (Q = n × Q_single, where n=3), allowing longer current supply per Faraday's law of electrolysis or basic battery runtime formula t = Q/I.
Why the others are wrong:
- B: Parallel fixes e.m.f. at 1.5V; no variable output without switching.
- C: E.m.f. per coulomb stays 1.5V, same as single cell (work per charge = V).
- D: Parallel e.m.f. is 1.5V, not additive to 4.5V (that's series).
Final answer: A
Topic: Electromotive force and potential difference
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