Question 19M.2.HL.TZ1.8b.iii
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.2.HL.TZ1.8b.iii |
| Level | HL | Paper | 2 | Time zone | TZ1 |
| Command term | Suggest | Question number | b.iii | Adapted from | N/A |
A student makes a parallel-plate capacitor of capacitance 68 nF from aluminium foil and plastic film by inserting one sheet of plastic film between two sheets of aluminium foil.
The aluminium foil and the plastic film are 450 mm wide.
The plastic film has a thickness of 55 μm and a permittivity of 2.5 × 10−11 C2 N–1 m–2.
The student uses a switch to charge and discharge the capacitor using the circuit shown. The ammeter is ideal.
The emf of the battery is 12 V.
Suggest one change to the discharge circuit, apart from changes to the coil, that will increase the maximum induced emf in the coil.
[2]
decrease/reduce ✔
resistance (R) OR capacitance (C) ✔
Candidates who recognized that something about the discharge circuit (not the charging circuit) needed to be changed generally suggested that something had to change with the resistance or capacitance. It should be noted that even though this was the last question on the exam, it was attempted at a higher rate than many of the other questions on the exam.
