# A student sets up two identical resistors, one connected in series with a power supply and one connected in parallel with a second identical resistor across the same power supply. Explain why the total resistance of the parallel arrangement is lower than the total resistance of the series arrangement.

> OCR A-Level Physics B: Advancing Physics (H557) — 3.4 Materials · Explain · 5 marks

> Two resistors, each with a resistance of 4 Ω, are available. In arrangement A, both resistors are connected in series. In arrangement B, both resistors are connected in parallel.

## Mark scheme (5 marks)

1. In the series arrangement, the total resistance is equal to the sum of the individual resistances
2. In the series arrangement, all the charge/current must flow through both resistors, making it harder for current to flow
3. In the parallel arrangement, the current splits so charge has more than one path/branch to take
4. Because charge can take more than one path, it is easier for current to flow overall, so the total resistance is lower
5. The total resistance in the parallel arrangement is less than the resistance of either individual resistor / less than the smallest individual resistance

## Key terms

- [series](https://www.gradenine.co.uk/glossary/series)
- [parallel](https://www.gradenine.co.uk/glossary/parallel)
- [total resistance](https://www.gradenine.co.uk/glossary/total-resistance)

## Related

- [Revision notes for OCR A-Level Physics B: Advancing Physics (H557)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-sets-up-two-identical-0a03048d) · Published by Druglandscape Ltd.