19.3. Discharging a capacitor
A subsection of Physics, 9702, through 19. Capacitance
Listing 10 of 24 questions
A capacitor C is charged using a supply of e.m.f. 8.0 V. It is then discharged through a resistor R. The circuit is shown in . 8.0V C R The variation with time t of the potential difference V across the resistor R during the discharge of the capacitor is shown in . 0.5 1.0 1.5 2.0 V / V t / s During the first 1.0 s of the discharge of the capacitor, 0.13 J of energy is transferred to the resistor R. Show that the capacitance of the capacitor C is 4500 µF. Some capacitors, each of capacitance 4500 µF with a maximum working voltage of 6 V, are available. Draw an arrangement of these capacitors that could provide a total capacitance of 4500 µF for use in the circuit of .
9702_s08_qp_4
THEORY
2008
Paper 4, Variant 0
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Explain what is meant by the capacitance of a parallel plate capacitor. A parallel plate capacitor C is connected into the circuit shown in . 120 V A X Y S C 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 the charge, in coulomb, passing through the ammeter in 1.0 s, charge = C the charge on one plate of the capacitor, each time that it is charged, charge = C the capacitance of capacitor C. capacitance = F 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.
9702_s18_qp_41
THEORY
2018
Paper 4, Variant 1
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Explain what is meant by the capacitance of a parallel plate capacitor. A parallel plate capacitor C is connected into the circuit shown in . 120 V A X Y S C 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 the charge, in coulomb, passing through the ammeter in 1.0 s, charge = C the charge on one plate of the capacitor, each time that it is charged, charge = C the capacitance of capacitor C. capacitance = F 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.
9702_s18_qp_43
THEORY
2018
Paper 4, Variant 3
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A bridge rectifier contains four diodes. The output of the rectifier is connected to a resistor R, as shown in . bridge rectifier output resistor R input The variation with time t of the input e.m.f. E to the rectifier is given by the expression E = 15 cos(210t ) where t is measured in seconds and E in volts. The variation with time t of the potential difference V across resistor R is shown in . V t1 t2 time t Determine: the maximum potential difference VMAX across resistor R VMAX = V the time interval, to two significant figures, between time t1 and time t2. time = s
9702_s19_qp_41
THEORY
2019
Paper 4, Variant 1
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A bridge rectifier contains four diodes. The output of the rectifier is connected to a resistor R, as shown in . bridge rectifier output resistor R input The variation with time t of the input e.m.f. E to the rectifier is given by the expression E = 15 cos(210t ) where t is measured in seconds and E in volts. The variation with time t of the potential difference V across resistor R is shown in . V t1 t2 time t Determine: the maximum potential difference VMAX across resistor R VMAX = V the time interval, to two significant figures, between time t1 and time t2. time = s
9702_s19_qp_43
THEORY
2019
Paper 4, Variant 3
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Questions Discovered
24