An electrical cable is made up of one thick strand of copper wire that is surrounded by eight thin strands of copper wire. All nine strands of wire are connected in parallel with each other.
A cross-section of the cable is shown.
[Figure 32.1]
Each thin strand of wire has cross-sectional area A and length L.
The thick strand of wire has cross-sectional area 4A and length L.
The cable has total resistance R.
Which expression gives the resistivity of copper?

Q: What topic does this question test?

This question tests Electricity in A-Level Physics (syllabus code 9702). It is worth 1 mark.

Q: Which exam paper is this question from?

This question appeared in the Cambridge A-Level Physics May/June 2023 examination, Paper 1 Variant 2 (9702_s23_qp_12.pdf).

Question

An electrical cable is made up of one thick strand of copper wire that is surrounded by eight thin strands of copper wire. All nine strands of wire are connected in parallel with each other.
A cross-section of the cable is shown.
[Figure 32.1]
Each thin strand of wire has cross-sectional area A and length L.
The thick strand of wire has cross-sectional area 4A and length L.
The cable has total resistance R.
Which expression gives the resistivity of copper?

Oracle Prep · Accepted Answer

The correct answer is D: 12AR / L.

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