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2 marksElectrical Circuits

CAPE Physics Unit 2 · 2016 · Paper 2 · Question 1(b)(i)

An experiment to find the internal resistance of a 9 V battery using a precision resistance box and a digital multimeter ammeter.

Measurements of current, I_L, are recorded as the external resistance, R_L, is varied. Show that for this circuit, the relationship between the measured current, I_L, and the external resistance, R_L, can be expressed by the equation R_L = I_L^{-1} V_B - R_i.

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Other parts of this question

  1. 1(a)(i)Explain how terminal potential difference, internal resistance and ideal source are related in a practical source of electromotive force (e.m.f.) such as an…[3 marks]
  2. 1(a)(ii)State TWO qualitative practical observations which demonstrate the existence of internal resistance.[2 marks]
  3. 1(b)(ii)Complete Table 1 by inserting the appropriate values in Column 3 for (I_L)^{-1} / \text{Amp}^{-1}.[1 mark]
  4. 1(b)(iii)On the grid provided in Figure 2, plot a graph of I_L^{-1} versus R_L and draw the best straight line through the points. Choose appropriate scales to…[4 marks]
  5. 1(b)(iv)Determine and record the intercept on the I_L^{-1} axis.[1 mark]
  6. 1(b)(v)Use the intercept along with the equation given in (b)(i) to determine the internal resistance of the battery.[2 marks]

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