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CAIE IGCSE Physics 4.2.4.5 Following Relationship for a Metallic Questions

Practise applying resistance proportional to length and inversely proportional to cross-sectional area, converting diameter changes into area factors for wires.

Syllabus
2026–2028
Course
Physics 0625

Exam points

  • Apply R proportional to length for wires of the same material, apply R proportional to 1/A and square any diameter factor, and combine length and area ratios to calculate or rank resistances.

CAIE IGCSE Physics 4.2.4.5 Following Relationship for a Metallic Questions question 1

[Maximum number: 4]

A cylinder is made of modelling clay. The modelling clay is an electrical conductor.
Fig. 8.1 shows the cylinder.

Fig. 8.1

Fig. 8.1

The cylinder is connected into a circuit.
Fig. 8.2 shows that the circuit also includes a battery of electromotive force (e.m.f.) 9.0 V and a resistor P.

Fig. 8.2

Fig. 8.2

The resistance of P is 4.0Ω4.0 \Omega. The current in P is 1.5 A .

The cylinder is removed from the circuit and replaced with a new cylinder made of the same modelling clay.

The new cylinder is twice the length and has half the cross-sectional area of the first cylinder. Calculate the time that it now takes for a charge of magnitude X to flow through resistor P.

time =

[Total: 9]

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