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4.2 Electrical quantities

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Question 18

A student investigates how the resistance of a wire depends on its length.

Plan an experiment to investigate the relationship between the length of a wire and its electrical resistance.

Resistance is calculated using the equation R=VI\displaystyle R = \frac{V}{I}R=IV​.

The following apparatus is available:

  • ammeter
  • voltmeter
  • d.c. power supply
  • metre rule
  • a long constantan (resistance) wire taped to a ruler
  • connecting leads and crocodile clips

You can also use other apparatus and materials that are usually available in a school laboratory.

In your plan, you should:

  • draw a diagram of a suitable electrical circuit using standard electrical symbols
  • explain briefly how to carry out the investigation, including how to measure different lengths and how to obtain the measurements needed to calculate resistance
  • state the key variables to keep constant to ensure a fair test
  • draw a table, with column headings and units, to show how to display your readings (you are not required to enter any readings in the table).
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Markscheme

4.2 Electrical quantities Questions

  1. IGCSE
  2. /Physics
  3. /4.2 Electrical quantities

452 exam-style questions on CIE IGCSE Physics 4.2 Electrical quantities, covering 4.2.1a Positive and negative charge, 4.2.1b Charging by friction and detecting charge, 4.2.1c Electrical conductors and insulators, 4.2.1d Electric fields and electric field patterns, 4.2.2a Electric current, charge and measuring current, 4.2.2b Conduction in metals and the direction of current, 4.2.2c Direct current and alternating current, 4.2.3a Electromotive force, 4.2.3b Potential difference and voltmeters, 4.2.4a Resistance, 4.2.4b Resistance of a metallic wire, 4.2.4c Current–voltage graphs, and 4.2.5 Electrical energy and electrical power. Each one has a worked solution and a mark scheme showing where the marks go.

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