WPH13 Practical Skills in Physics I

Lessons in WPH13

1. The Unit 3 practical skills paper and command words
   Plan, implement, process. Read the command word, make every point specific to the apparatus, show working, give units, and give 'show that' answers to one more
2. Planning: variables, range and a fair test
   Change one variable, measure one, control the rest (and say how). At least six values over a wide range; distinguish repeats from extra values; say which graph
3. Choosing instruments: range and resolution
   Resolution is the smallest interval an instrument can show. Choose one whose range covers the measurement and whose resolution gives a small percentage uncertai
4. Reading vernier calipers and micrometers; zero error
   Vernier: main scale + aligned line x 0.1 mm. Micrometer: sleeve + thimble x 0.01 mm, closed with the ratchet. Subtract the zero reading. Measure at several plac
5. Measurement techniques that reduce uncertainty
   Clamp, check vertical with a set square, read perpendicular to the scale. Time many oscillations past a marker at equilibrium. Measure many identical items toge
6. Random and systematic errors; accuracy and precision
   Random errors scatter readings: repeat and average. Systematic errors shift every reading: correct, calibrate or redesign. Precise means close together; accurat
7. Uncertainty from resolution and percentage uncertainty
   Single reading: uncertainty = half the resolution. Percentage uncertainty = uncertainty / value x 100%, to 1 or 2 s.f. Bigger measurements give smaller percenta
8. Repeat readings: mean, half range and anomalies
   Mean to the same decimal places as the data. Uncertainty = half the range (or furthest value from the mean). Percentage = half range / mean x 100. Repeat anomal
9. Significant figures and decimal places
   Raw data to the instrument's resolution, consistent decimal places in a column. Results to the s.f. of the least precise data (usually 2 or 3). Never round mid-
10. Recording results in tables and criticising data
    Headings: quantity / unit. Consistent decimal places. At least six values over a wide range, with repeats. Name any anomaly specifically.
11. Processing results: units, prefixes and powers of ten
    Convert to SI first, with squared and cubed factors for areas and volumes. Use d²/4 with diameters. Energy in, energy out. Efficiency is always under 100%.
12. Plotting graphs: axes, scales, points and best-fit lines
    y against x as asked; quantity / unit labels; scales of 1, 2 or 5 per square filling over half the grid; small crosses within 1 mm; one thin ruled line balancin
13. Gradients and intercepts
    Large triangle (over half the line), corners on the line, Δy/Δx with sign and unit. Read the intercept only at x = 0; otherwise c = y - mx. Compare with y = mx
14. Linearising relationships to y = mx + c
    Rearrange into y = mx + c with constants in m and c. State that the gradient is a constant (named) and the intercept is zero where predicted; a straight line co
15. Uncertainty in a result: what Unit 3 expects
    Unit 3: half the resolution for one reading, half the range for repeats. Add the absolute uncertainties of two readings that are added or subtracted. Dividing b
16. Comparing results with accepted values and drawing conclusions
    Limits from your own percentage uncertainty; check whether the accepted value is inside; say so explicitly. Or compare the percentage difference (accepted value
17. Safety in physics practicals
    Name the specific hazard and a precaution that controls it. Generic advice, ordinary goggles for lasers and extra unasked-for points are not credited.
18. Electrical measurements: circuits, meters and components
    Standard symbols; ammeter in series, voltmeter across only the component. A protective resistor limits current; check its power rating exceeds the power dissipa
19. Practical skills in core practicals 1 to 3
    CP1: h against t², gradient g/2, intercept reveals a release delay. CP2: equal times between band pairs show terminal velocity; diameter squared. CP3: long thi
20. Practical skills in core practicals 4 to 6
    CP4: T = divisions x time base, measure over many cycles and wavelengths; λ against 1/f gives v. CP5: approach resonance from both sides. CP6: large D, measure
21. Practical skills in core practicals 7 and 8
    CP7: R against l, ρ = gradient x A; intercept = contact resistance; diameter squared dominates the uncertainty. CP8: V against I, gradient -r, intercept ε; prot
22. Writing a plan: extended-response questions
    List measurements and instruments, techniques, the range and number of values, controls (and how), repeats, the graph and what its gradient gives, the main unce

Next exams for WPH13

• January 2027: Fri 15 Jan 2027, afternoon, 1h 20m
• Summer 2027: Wed 19 May 2027, afternoon, 1h 20m

From Pearson's final timetables. All exam dates. Always confirm your entries with your exams officer.