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.

1. (a)Explain what is meant by the capacitance of a parallel plate capacitor.[3]
2. (b)(i)the charge, in coulomb, passing through the ammeter in 1.0s, charge = .............................................. C[1]
3. (b)(ii)the charge on one plate of the capacitor, each time that it is charged, charge = .............................................. C[1]
4. (b)(iii)the capacitance of capacitor C. capacitance = .............................................. F[2]
5. (c)Suggest and explain the effect on the current recorded on the ammeter.[2]

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