Effective laboratory work combines experimental skill with rigorous data analysis.
Before the experiment
- Read the theory and predict the expected result.
- Identify which variables to control, vary, and measure.
- Estimate the required precision and choose appropriate instruments.
During the experiment
- Record raw data immediately in a table with units.
- Take at least 5 repeated measurements for each data point.
- Note any anomalies or unexpected observations.
After the experiment
| Step | Action |
|---|---|
| 1 | Calculate means and standard errors |
| 2 | Plot data with error bars |
| 3 | Fit a line or curve |
| 4 | Extract physical quantities from fit parameters |
| 5 | Propagate uncertainties to the final result |
| 6 | Compare with accepted values |
Assessing agreement — Two results and agree if:
Common pitfalls
- Discarding "bad" data without a valid statistical reason.
- Confusing the uncertainty in a single measurement with the uncertainty in the mean.
- Forgetting to include units at every stage of calculation.
Tip: The goal is not to "get the right answer" but to demonstrate understanding of the physics and honest analysis of the data. A well-analysed "wrong" result with good error bars is better than an unexplained "right" one.
Common pitfall: Two results disagree only if their uncertainty intervals fail to overlap. Comparing bare central values — declaring 9.79 "wrong" because the handbook says 9.81 — ignores the very error analysis the lab exists to teach.