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3 marksElectrical Circuits

CAPE Physics Unit 2 · 2007 · Paper 2 · Question 4(a)(iv)

A cell has an e.m.f. of 1.51 V as measured by a potentiometer. When a 5.0 Ω resistor is connected in parallel with the cell, the terminal p.d. falls to 1.26 V. Calculate the internal resistance of the cell.

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Other parts of this question

  1. 4(a)(i)Explain why the electromotive force (e.m.f.) of a battery is not necessarily equal to the potential difference across its terminals.[2 marks]
  2. 4(a)(ii)Describe in detail, with the aid of a diagram, how a slide-wire potentiometer can be used to determine the e.m.f. of a battery, assuming a standard cell with…[5 marks]
  3. 4(a)(iii)Explain why a potentiometer is expected to give a more accurate measurement of e.m.f. than a moving coil voltmeter.[2 marks]
  4. 4(b)(i)Calculate the values of currents x and y.[6 marks]
  5. 4(b)(ii)Determine the potential difference between points P and Q.[2 marks]

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