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AS Daily A Level Physics question

2026-01-20 OCR A Materials: springs in series/parallel 3.4.1(c)

A desk lamp of weight W is hung from the ceiling using two identical springs, each with the same stiffness k. You can arrange the springs either in series (end-to-end as one hanger) or in parallel (side-by-side sharing the load from the same hook to the lamp). Compared to using a single spring, which statement about the lamp’s extension must be true for the same weight W?

  1. A Series produces twice the extension of one spring; parallel produces half the extension. (correct)
  2. B Series produces half the extension of one spring; parallel produces twice the extension.
  3. C Both arrangements produce the same extension as one spring.
  4. D Both arrangements produce twice the extension of one spring.

Answer

The correct answer is A.

Correct: A — Series produces twice the extension of one spring; parallel produces half the extension. B — This reverses the effect: in series the same force stretches both springs so the extension adds (doubling), while in parallel each spring takes about W/2 so the extension halves. C — This ignores that load distribution changes: in series the extension adds, and in parallel the load per spring is reduced. D — Only the series case doubles the extension; in parallel the extension is reduced to about half, not doubled.

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