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CAPE Physics Unit 2 · May/June 2025 · Paper 2 · Question 1(b)(ii)

In an experiment to measure the resistivity of an unknown metal, ρ, a sample of the metal was drawn into a wire of diameter 2 mm and length 30 m. A current of 2 A was passed through the wire and the voltage drop, V, across different lengths of wire, L, was measured and recorded in Table 1.

Determine the gradient of your graph in (b)(i).

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Other parts of this question

  1. 1(a)(i)Explain, in terms of electron movement, how drift velocity occurs in metals.[4 marks]
  2. 1(a)(ii)Consider a cylindrical piece of metal of length, d, cross-sectional area, A, and number density of charges, n. Derive the equation relating current in the…[5 marks]
  3. 1(a)(iii)A DC generator supplies a current of 10 A to a load through a distribution line. The distribution line is a solid copper conductor of diameter 2.0 mm. The free…[4 marks]
  4. 1(b)(i)On the grid provided in Figure 1 on page 7, plot a graph of voltage drop versus length. Draw the line of best fit through the points.[4 marks]
  5. 1(b)(iii)Derive an expression for the gradient in terms of ρ, the resistivity of the wire.[3 marks]
  6. 1(b)(iv)Hence, determine ρ, the resistivity of the unknown metal.[2 marks]
  7. 1(b)(v)Calculate the power dissipated by the wire during the experiment.[1 mark]
  8. 1(b)(vi)Calculate the energy drawn from the power supply if the experiment runs for a total of 15 minutes.[3 marks]
  9. 1(b)(vii)State ONE assumption made about the wire in the experiment.[1 mark]

More practice: the rest of this paper · more Electrical Quantities questions · all CAPE Physics Unit 2 past papers