Question 22N.2.HL.TZ0.d
| Date | November 2022 | Marks available | [Maximum mark: 2] | Reference code | 22N.2.HL.TZ0.d |
| Level | HL | Paper | 2 | Time zone | TZ0 |
| Command term | Describe | Question number | d | Adapted from | N/A |
A parallel-plate capacitor of capacitance 1.5 × 10−10 F is made from two metal plates separated by an air gap of 1.0 mm. The capacitor is initially charged to a potential difference of 24 V.
The charged capacitor is disconnected from the voltage supply and the separation between the plates is increased to 4.0 mm.
The capacitor is then discharged through a fixed resistor. The initial current in the resistor is and the time constant of the circuit is .
A diode bridge rectification circuit is often modified by adding a capacitor in parallel with the output (load) resistance.
Describe the reason for this modification.
[2]
without a capacitor, output voltage/current drops to zero «twice per cycle of input voltage» ✓
capacitor provides smoothing / smooths out voltage/current variations ✓
voltage/current output becomes constant / similar to direct current output ✓
voltage/current does not drop to zero ✓
by returning some of its energy/charge to the circuit «when input voltage is low» ✓
Generally, candidates either made a good job of this, suggesting a number of credit worthy points or had no idea and guessed something to do with resistances/capacitances in parallel.
