Cambridge International AS & A Level · P5 · structured
Read a stored low-voltage trace
A2 practical 3: use an oscilloscope as a measuring instrument · Original GioPhysics question with a detailed, mark-by-mark answer guide.
- Demand
- demanding
- Marks
- 7
- Topics
- 1
- Answer
- Complete
Constructed scope observations with x1 probe: a symmetric wave spans 6.0 vertical divisions at 0.20 V/div; five cycles span 8.0 horizontal divisions at 0.50 ms/div. A separate stored pulse across a 50 ohm sense resistor is 2.5 divisions high at 0.10 V/div. Find V_pp, amplitude, period, frequency and pulse current. Describe single-shot capture and the required common-ground precaution.
- (a)
Find voltage and timing quantities.
4 marks - (b)
Determine pulse current.
1 mark - (c)
Describe storage acquisition and grounding.
2 marks
Ready to self-mark?Reveal the detailed answer guide
(a)
Find voltage and timing quantities.
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
1.2 V peak-to -peak, 0.60 V amplitude, 0.80 ms period, 1.25 kHz before reporting-rounding.
(b)
Determine pulse current.
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
5.0 mA.
(c)
Describe storage acquisition and grounding.
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
Trigger/store event with settings; ground only at checked common return.
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.
- V_pp=6.0x0.20=1.2 V and amplitude=0.60 V: 2 marks.
- T=8.0x0.50/5=0.80 ms and f=1250 Hz: 2 marks.
- I=(2.5x0.10)/50=0.0050 A: 1 mark.
- Single-shot acquisition/trigger before event and retain settings with stored trace: 1 mark.
- Common/earth reference checked; no ground clips on separate live nodes: 1 mark.
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