# A scientist is investigating how two resistors can be connected in a circuit. Explain why connecting two identical resistors in parallel gives a smaller total resistance than connecting just one of those resistors alone in the circuit.

> OCR A-Level Physics B: Advancing Physics (H557) — 3.1 Motion · Explain · 5 marks

> Two identical resistors, each with a resistance of 6 Ω, are available. The scientist considers connecting them in two different ways: using only one resistor, or connecting both resistors in parallel.

## Mark scheme (5 marks)

1. In a parallel circuit, the current splits into two separate branches
2. Only some of the charge flows along each branch (not all charge passes through both resistors)
3. Adding a second parallel branch provides an additional path for current, making it easier for charge to flow overall
4. The total resistance in a parallel arrangement is less than the smallest individual resistance
5. With only one resistor, all the charge must pass through that single resistor, making it harder for current to flow, so resistance is higher

## Key terms

- [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-scientist-is-investigating-how-two-b4b04a32) · Published by Druglandscape Ltd.