Question 23M.2.HL.TZ2.7
| Date | May 2023 | Marks available | [Maximum mark: 8] | Reference code | 23M.2.HL.TZ2.7 |
| Level | HL | Paper | 2 | Time zone | TZ2 |
| Command term | Calculate, Draw, Explain, Sketch, State | Question number | 7 | Adapted from | N/A |
Three identical secondary coils, P, Q and R, are wound onto the iron core of a transformer.
The coils form a power supply that provides two output voltages, one between A and B and another between C and D.
The primary coil of the transformer is connected to a 110 V rms mains supply.
The primary coil has 1500 turns. Each secondary coil has 75 turns.
Two of the secondary coils, P and Q, are connected in series to a diode bridge.
There is no load resistor between A and B.
X and Y are points in the circuit connected to the ends of the coils.
Calculate the peak emf between X and Y.
[2]
Use of OR correct conversion of rms to peak value at some point ✓
16 «V» ✓
The graph shows the variation with time of the output emf between X and Y.
Draw, on the graph, the variation with time of the potential difference between A and B. You do not need to put numbers on the axes.
[1]
✓
A resistor is now connected between A and B.
State and explain the reason why the peak potential difference across XY will be smaller than the emf you calculated in (a)(i).
[2]
There is now a current in the secondary coils ✓
Energy loss due to heating in the coils
OR
«Lenz’s law predicts that» this will oppose the original induced emf ✓
«and reduce the pd across the coils»
Coil R is connected to a single diode and a load that consists of a capacitor and a resistor.
The graph shows the variation with time of the potential difference across coil R.
Sketch, on the graph, the potential difference between C and D.
[1]
✓
State and explain the effect of adding another capacitor in parallel with the original capacitor.
[2]
Adding a capacitor in parallel will increase the capacitance / will increase RC ✓
idea that this makes the waveform smoother ✓