Context and communication: physics in technology, society and everyday life; presentation and argumentation
What this domain tests
Context and communication asks you to place physics in technology, society and everyday life and to present and argue a case with it. Questions typically supply a short text, a data table or a device diagram and ask you to take a position - on energy supply, radiation exposure, medical imaging or electromobility - and justify it with calculation.
Using physics as evidence
- Turn the qualitative claim into numbers: an electric car with a 60 kWh battery and 400 km range uses 15 kWh per 100 km; compare that with a petrol car at about 8 l/100 km.
- Compare orders of magnitude first; say which contribution dominates.
- State the model boundary: comparing efficiencies is only fair at the same boundary (tank-to-wheel versus well-to-wheel).
Presenting an argument
- Structure: question, assumptions, calculation, result with unit and uncertainty, evaluation, conclusion.
- Use diagrams with labelled axes, field lines and units - information, not decoration.
- Separate verified data from estimates and say where each number comes from.
- Distinguish hazard from risk (probability times consequence), and activity (Bq) from dose (Sv).
Society and technology
- Power is energy per unit time; a device's energy use is power times operating time, which settles most standby-consumption arguments.
- Efficiency chains matter: a coal plant at about 40 %, a heat pump with a coefficient of performance around 3 and a battery round trip near 90 % cannot be compared directly.
- Discuss benefit together with burden: MRI involves no ionising dose but needs cryogenics and helium; a CT scan delivers a real effective dose in the millisievert range.
Worked example
An 8 W LED lamp and a 60 W incandescent lamp are each used 3 h per day for a year. LED: 8 W · 3 h · 365 = 8.8 kWh; bulb: 60 W · 3 h · 365 = 65.7 kWh. At 0.35 €/kWh the difference is roughly 20 € per year per lamp. That figure, not the adjective "much more efficient", is what earns the marks.
Traps
- Confusing power and energy, or kW and kWh.
- Making a policy claim with no number attached.
- Ignoring the boundaries of a comparison so the conclusion overstates itself.
- Presenting an opinion as a measured fact, or quoting a number without its source.