Tools and Inquiry — IB Physics skills
Tools and Inquiry — IB Physics skills — IB Physics SL Revision Notes & Topical Questions
5 min read 10 parts Lesson 1 of 33 Unit quiz
Lesson summary
Tools and Inquiry — IB Physics skills — IB PHYSICS SL notes: Apply safe, ethical and environmentally aware technique, choose measuring instruments, use SI units and prefixes, and combine and resolve vectors.Risk assessment = identifying hazards, judging the level of risk and chan…
- Protective wear
- Glassware can break
- Electricity use
- Perpendicular vectors
- Resolving a vector
- Explore and design
Part 1 of 7Specific hazards and precautions
| Apparatus | Hazard | Precaution |
|---|---|---|
| Radioactive sources | Ionising radiation | Lead-lined labelled storage, shortest time, tongs, never pointed at anyone, safe distance, trained teacher |
| Electron diffraction | High voltage | Qualified staff only, earthed and checked, no touching live connections |
| Lasers | Eye damage | Never aim at people or reflective surfaces, beam horizontal below eye level, goggles, switch off after use |
| Electrical circuits | Shock, heating | Low voltage (1.5 V cells, up to 9 V), check earthing of 12–15 V supplies, no bare wires or water |
| Hot water and gas pressure | Scalds, glass breakage | Keep from table edges, never leave unattended, gloves with bungs, shield glass tubes, do not overfill syringes |
Part 2 of 7Ethical and environmental issues
Ethics
- Ethics physics rarely raises major ethical concerns.
- Human subjects need informed consent and animal work needs ethical protocols.
- If you find no ethical concern you may say so, with a justification.
Electricity use
- Electricity use mains power relies partly on fossil fuels, so switch off equipment and use low-voltage supplies.
Water use
- Water use reuse the same water across trials and never pour oily or contaminated water down a drain.
Batteries
- Batteries wrong disposal risks fire and toxic release, so recycle them or use rechargeable cells.
Waste
- Waste reuse or recycle materials and state how you will reduce any environmental impact.
Part 3 of 7Choosing instruments
| Quantity | Instrument | Notes |
|---|---|---|
| Mass | Digital balance | Tare first; record in kg |
| Time | Stopwatch or stop-clock | Reaction time matters below one second |
| Length | Ruler (1 mm), tape measure, micrometer | Standard unit is the metre |
| Volume | Measuring cylinder | 1 mL of water = 1 cm3; level change gives volume of an irregular solid |
| Temperature | Liquid thermometer or digital probe | Probes read to ±0.1 °C and suit data logging |
| Force | Force meter (spring balance) | Read in newtons |
| Current and p.d. | Ammeter in series, voltmeter in parallel | Check zero error; read analogue meters perpendicular to the scale |
Part 4 of 7SI units and prefixes
SI units and prefixes
Seven SI base units underpin all measurements.
- Length metre (m), mass kilogram (kg), time second (s), electric current ampere (A).
- Temperature kelvin (K), amount of substance mole (mol) and luminous intensity candela (cd), which is not used in IB Physics.
Prefixes show powers of ten and are listed in the data booklet.
- kilowatt kW = 103 W, centimetre cm = 10-2 m and milligram mg = 10-3 g.
Part 5 of 7Vectors and scale drawing
Scalar
Scalar magnitude only, such as mass — vector = magnitude and direction.
Add vectors head to tail (or by the parallelogram method) to get the resultant.
- c = a − b is a + (−b), the reverse of b added.
Perpendicular vectors
- Pythagoras gives the magnitude and trigonometry the angle.
Resolving a vector
- Fx = F cos θ and Fy = F sin θ, when θ is measured from the x-axis.
Scale drawing for non-perpendicular vectors.
- Choose a scale, such as 1 cm = 1 km, and draw accurately with a sharp pencil, ruler and protractor.
- Measure the resultant length and angle (a bearing from North if needed) and convert with the scale.
Part 6 of 7Inquiry process and uncertainty
1Explore and design
- Explore and design a focused research question, identifying independent, dependent and control variables.
2Collect data with units and uncertainties
- Collect data with units and uncertainties then process with means, graphs and gradients.
3Conclude by linking results to the research question and theory
- Conclude by linking results to the research question and theory then evaluate systematic and random errors and suggest improvements.
4Quote a measurement as value ± absolute uncertainty
- Quote a measurement as value ± absolute uncertainty percentage uncertainty = absolute ÷ value × 100%.
5Add absolute uncertainties for addition and subtraction
- Add absolute uncertainties for addition and subtraction add percentage uncertainties for multiplication and division.
6
A negligible effect is much smaller than the others and can be ignored.
- Examples are heat loss in specific heat capacity work and string mass in a simple pendulum.
Part 7 of 7More from the specification
1Precision of instrumental readings to decimal places
- Precision of instrumental readings to decimal places recording burette and micrometer measurements to two decimal places maintains consistent reporting precision.
2Instrument Resolution and Precision
- Selecting digital multimeters, light meters,
- or calipers with high precision minimizes reading uncertainty during quantitative physics experiments.
3Safety and Risk Assessment in Investigations
- Identifying potential physical hazards (such as intense laser light sources, high voltages,
- or hot heating coils) ensures laboratory safety precautions are enforced.
4Environmental and Ethical Issues
- Practical investigations must evaluate environmental issues related to electrical energy consumption and safe recycling of chemical cells and heavy metal components.
5Digital Displays and Parallax Error
- Using instruments with digital displays eliminates analogue scale reading errors and parallax, yielding more reproducible experimental data.
6Instrument Resolution and Precision
- Selecting digital multimeters, light meters,
- or calipers with high precision minimizes reading uncertainty during quantitative physics experiments.
7Safety and Risk Assessment in Investigations
- Identifying potential physical hazards (such as intense laser light sources, high voltages,
- or hot heating coils) ensures laboratory safety precautions are enforced.
8Environmental and Ethical Issues
- Practical investigations must evaluate environmental issues related to electrical energy consumption and safe recycling of chemical cells and heavy metal components.
9Digital Displays and Parallax Error
- Using instruments with digital displays eliminates analogue scale reading errors and parallax, yielding more reproducible experimental data.
10Decimal place
- A digit to the right of the decimal point.
11Precision
- How close repeated measurements are to each other.
12Potential difference
- Work done by a unit charge passing through a component.
Key terms
| Term | Meaning |
|---|---|
| SI unit | Unit in the international system, such as metre, kilogram or second. |
| Prefix | Power-of-ten multiplier such as kilo or milli. |
| Resultant vector | Single vector produced by adding or subtracting vectors. |
| Component | Perpendicular part of a vector found by resolving. |
| Risk assessment | Identifying hazards, judging the risk and reducing it. |
| Negligible | Small enough to ignore without changing the result noticeably. |
| Tare | To set a balance to zero before weighing. |
Avoid these mistakes
1
Using scale drawing without stating the scale or converting the measured length back.
2
Taking F cos θ as the vertical component — it is the component along the axis from which θ is measured.
3
Saying there are no environmental issues without considering electricity, water and batteries.
4
Forgetting to tare a balance before weighing.
5
Connecting a voltmeter in series or an ammeter in parallel.
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