Cambridge International AS & A Level · 21 · structured
Explain rectification with both conducting loops
Trace both paths through a four-diode bridge · Original GioPhysics question with a detailed, mark-by-mark answer guide.
- Demand
- demanding
- Marks
- 8
- Topics
- 1
- Answer
- Complete
Draw the four-diode bridge described by D1:A→P, D2:B→P, D3:N→A and D4:N→B, with AC across A–B and a load across P–N. Trace the complete current route in each half-cycle and explain why load current does not reverse. For a 50 Hz sinusoidal supply without smoothing, state the output pulse frequency and whether the output voltage is constant.
- (a)
Draw the complete correctly oriented bridge circuit.
2 marks - (b)
Trace and explain both half-cycle loops.
4 marks - (c)
State output pulse frequency and whether the voltage is constant.
2 marks
Ready to self-mark?Reveal the detailed answer guide
(a)
Draw the complete correctly oriented bridge circuit.
Identify what the question is testing, organise the response into distinct mark-earning points, and make every conclusion traceable to a physical principle or to the evidence supplied.
- 1
Four diodes with stated anode/cathode directions; correct source and load diagonals.
(b)
Trace and explain both half-cycle loops.
Identify what the question is testing, organise the response into distinct mark-earning points, and make every conclusion traceable to a physical principle or to the evidence supplied.
- 1
D1/D4 and D2/D3 respectively, both load P→N; other pair blocks.
(c)
State output pulse frequency and whether the voltage is constant.
Identify what the question is testing, organise the response into distinct mark-earning points, and make every conclusion traceable to a physical principle or to the evidence supplied.
- 1
100 Hz; unsmoothed pulsating DC, not constant.
Complete marking guidance
Use these worked steps alongside the part-by-part answers. They explain the method and mark allocation; they do not add extra marks.
- Draw four correctly oriented diodes, the AC source between A and B and the load between P and N.
- A positive: A→D1→P→load→N→D4→B, returning through the source.
- B positive: B→D2→P→load→N→D3→A, returning through the source.
- Each pair steers current through the load from P to N, while the other two diodes block.
- There are two output pulses per input cycle: 2×50 = 100 Hz.
- With no smoothing capacitor the voltage still falls to zero at input zero crossings.
Private on this device