A-LevelPhysicsCapacitanceMay/June 2018Paper 4 Q79 Marks
7 (a) Explain what is meant by the capacitance of a parallel plate capacitor. (b) A parallel plate capacitor C is connected into the circuit shown in Fig. 7.1. [Figure 7.1] When switch S is at position X, the battery of electromotive force 120 V and negligible internal resistance is connected to capacitor C. When switch S is at position Y, the capacitor C is discharged through the sensitive ammeter. The switch vibrates so that it is first in position X, then moves to position Y and then back to position X fifty times each second. The current recorded on the ammeter is 4.5 μA. Determine (i) the charge, in coulomb, passing through the ammeter in 1.0s, charge = .............................................. C (ii) the charge on one plate of the capacitor, each time that it is charged, charge = .............................................. C (iii) the capacitance of capacitor C. capacitance = .............................................. F (c) A second capacitor, having a capacitance equal to that of capacitor C, is now placed in series with C. Suggest and explain the effect on the current recorded on the ammeter.
📋 Examiner Report & Trap Analysis
Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...
🎯 Mark Scheme Breakdown
Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.
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