Cambridge International AS & A Level · P3 · structured
Repair an incomplete laboratory record
AS practical 3: create the record before measuring · Original GioPhysics question with a detailed, mark-by-mark answer guide.
- Demand
- demanding
- Marks
- 9
- Topics
- 9
- Answer
- Complete
Using the constructed table, prepare the full table including the repeated observation, complete the missing resistances, and show one calculation, explaining why the resistance equation is appropriate. Explain why averaging and then deleting the repeated raw readings, writing 1.8 instead of 1.80 on this range, or reporting 100.0000 ohm is poor recording practice. Constructed illustrative data (not observed experimental evidence). Columns: Constructed row | V / V (raw) | I / mA (raw) | R / ohm (derived). Rows: 1 | 1.20 | 12.1 | 99.2; 2 | 1.80 | 18.0 | to calculate; 3 | 2.40 | 24.2 | to calculate; 3, repeat | 2.40 | 24.1 | keep separate raw row.
- (a)
Construct the complete record.
3 marks - (b)
Calculate the missing resistances, justify the equation and show working.
4 marks - (c)
Justify raw and derived precision.
2 marks
Ready to self-mark?Reveal the detailed answer guide
(a)
Construct the complete record.
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
One table, valid quantity/unit headings, distinct raw/derived columns, all repeat values preserved.
(b)
Calculate the missing resistances, justify the equation and show working.
List the given quantities with units, identify the required quantity, write the governing relationship before substituting, and keep extra digits until the final line so rounding does not distort the result.
- 1
100, 99.2 and 99.6 ohm; R=V/I follows the definition of resistance at the operating point; use I in A and show substitution.
(c)
Justify raw and derived precision.
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
Raw V values remain to 0.01 V; derived values to 3 or 4 sf from 3 sf inputs.
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.
- Award 2 marks for one prepared table containing quantity/unit headings and distinct raw/derived columns.
- Award 1 mark for retaining all original and repeated readings.
- Award 3 marks for R2=100 ohm, R3=99.2 ohm, Rrepeat=99.6 ohm with current converted to A.
- Award 1 mark for the resistance-definition justification, formula/substitution, and 1 for a correct significant-figure justification.
- Award 1 mark for explaining that raw decimal places represent the meter range, not cosmetic formatting.
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