# A technician tests two resistors, P and Q, by connecting each one separately to the same power supply. Resistor P allows a large current through it, while resistor Q allows only a small current through it. Explain what these results tell us about the resistance of P and Q, and describe, in terms of electrons and ions, why resistor Q opposes the flow of current more strongly than resistor P.

> Eduqas A-Level Physics — 2.1 Conduction and resistance · Explain · 5 marks

> Resistor P and resistor Q are made from different conducting materials. When connected to the same voltage, P carries a larger current than Q.

## Mark scheme (5 marks)

1. Resistor P has a lower resistance than resistor Q
2. A larger current means more charge (electrons) flowing per second / resistance opposes the flow of charge
3. In resistor Q, (positive) ions obstruct / collide with the moving electrons more (than in P)
4. These collisions transfer energy from the electrons / slow the electrons down, reducing the current
5. In resistor P, electrons move more freely / there are fewer obstructions, so current is greater

## Key terms

- [resistance](https://www.gradenine.co.uk/glossary/resistance)
- [current](https://www.gradenine.co.uk/glossary/current)
- [electrons](https://www.gradenine.co.uk/glossary/electrons)
- [ions](https://www.gradenine.co.uk/glossary/ions)

## Related

- [Revision notes for Eduqas A-Level Physics](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-technician-tests-two-resistors-p-584ed8d9) · Published by Druglandscape Ltd.