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2 marksElectrical Circuits

CAPE Physics Unit 2 · 2018 · Paper 2 · Question 2(e)

If the switching circuit turns on the floodlights whenever the voltage at its input falls below 7.5 volts, what should the value of R be?

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Other parts of this question

  1. 2(a)State the meaning of the acronym LDR, and briefly explain its operation.[4 marks]
  2. 2(b)Complete Columns 3 and 4 of Table 2 (log₁₀ R and log₁₀ Iᵥ).[2 marks]
  3. 2(c)On the grid provided in Figure 2, plot a graph of log₁₀ R against log₁₀ Iᵥ and draw the line of best fit through the points.[4 marks]
  4. 2(d)Use your graph from (c) to find the resistance of the LDR at a luminous intensity of 200 cd.[3 marks]

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