IB Physics SL
Tool 1 — Experimental Techniques
Paper 1, 2 & IA
Identify · assess · minimise
~7 min read
Safety, Ethics & the Environment
Before you switch on a single piece of apparatus, a good scientist has already thought about three things: could this hurt anyone, is it fair to everyone involved, and what does it do to the planet? These questions come up in the exam and are essential for your Internal Assessment — and the good news is there’s a simple, repeatable way to answer them.
📘 What you need to know
- Every practical needs a risk assessment: identify hazards, assess the level of risk, then minimise it
- A hazard is something that could cause harm; the risk is how likely and how serious that harm is
- Know the standard precautions for common physics kit: radioactive sources, lasers, high-voltage apparatus, hot water, and pressurised glassware
- Physics rarely raises big ethical issues, but human subjects need consent and animal work needs proper protocols
- If there’s no ethical concern, it’s fine to say so — but justify why
- Consider environmental impact: electricity use, water use, battery disposal, and waste — and explain how you’d reduce it
Safety: Identify, Assess, Minimise
Whenever you carry out an investigation, you must spot the safety hazards and manage the risks. The exam-friendly way to do this is a risk assessment, and it always follows the same three moves.
identify
the hazards
→ then →
assess
the risk
→ then →
minimise
the risk
It helps to keep two words separate. A hazard is anything with the potential to cause harm (a hot beaker, a live wire). The risk is the chance that it actually causes harm, and how bad that harm would be. A risk assessment identifies the hazards, judges the level of risk, and then alters the procedure to bring that risk down.
Hazard vs risk
hazard = potential to cause harm • risk = how likely + how serious
A jar of acid on a high shelf is a hazard. The risk is low while it sits there, but shoots up the moment someone reaches over it. Same hazard, different risk — which is exactly why “minimise the risk” is about changing what you do, not just noticing the danger.
Precautions for Common Apparatus
Different equipment brings different hazards, and examiners expect you to match a sensible precaution to the kit in front of you. Here are the ones that come up most in physics.
🧭 Standard precautions to remember
- Radioactive sources — store in lead-lined, labelled boxes; handle with tongs; never point at anyone; use for the shortest time; keep students at a safe distance under supervision
- Lasers — never aim at eyes or reflective surfaces; keep the beam horizontal and below eye level; wear laser goggles; switch off once done
- High-voltage apparatus (e.g. electron diffraction tubes) — set up by qualified staff only; ensure it’s earthed; never touch live connections
- Hot water & heating — keep apparatus away from table edges; never leave it unattended; don’t sit right beside beakers of hot water
- Pressurised glassware (Boyle’s law, gas syringes) — shield glass tubes with a screen; don’t overfill; handle gently, since most accidents come from carelessness
- General lab — wear goggles and gloves for hot, sharp, or chemical work; handle glassware carefully and don’t over-tighten stoppers
Quick recap: a risk assessment is identify → assess → minimise; a hazard can cause harm, the risk is how likely and serious it is; match a precaution to the apparatus (sources, lasers, high voltage, hot water, pressurised glass).
Ethical Issues
Physics rarely raises the big ethical questions you’d meet in biology or psychology, but you should still think it through. If your method could put anyone in an awkward or unfair position, that’s an ethical dilemma worth flagging.
- Human subjects — if people take part in your investigation (for example, timing their reactions), you need their informed consent.
- Animals — any work involving animals must follow the proper ethical guidelines and protocols.
- No concern? — it’s perfectly acceptable to state that your experiment has no significant ethical issues, as long as you justify why rather than just asserting it.
Don’t force an ethical worry where there isn’t one. For a pendulum experiment, “no human or animal subjects are involved, so there are no significant ethical concerns” is a complete, mark-worthy answer — the key is that little “because” clause.
Environmental Issues
Most physics practicals are gentle on the planet, but a careful scientist still considers their footprint — and, crucially, explains how they’d reduce it. Four areas come up again and again.
🧭 Environmental impacts and good practice
- Electricity use — mains power often comes from fossil fuels, releasing greenhouse gases. Switch off idle equipment, use low-voltage supplies, and choose energy-efficient devices
- Water use — reuse the same water across trials rather than running fresh each time, and never pour contaminated water down the drain if it holds oils or chemicals
- Battery use — improper disposal risks fire and leaks toxic chemicals into landfill. Recycle batteries, or use rechargeables or mains power where possible
- Waste reduction — reuse or recycle materials instead of discarding, and follow proper disposal methods
The exam rule is simple: if you identify an environmental concern, you must explain how you’ll reduce the impact of your investigation — naming the concern alone won’t get the mark.
WE 1A student investigates how the count rate from a radioactive source changes with distance. State two safety precautions they should take, and for each, explain how it reduces the risk.
Precaution 1
handle the source with tongs, never with bare hands
this increases the distance from the source and reduces exposure
→ lowers the dose received
Precaution 2
use the source for the shortest time possible and store it in a lead-lined box when not in use
lead absorbs the radiation and less time means less exposure
→ minimises total radiation dose
other valid points: keep a safe distance, never point it at anyone, supervised by a trained teacher
WE 2A circuit experiment uses several disposable batteries and a mains immersion heater. (a) Identify one environmental concern. (b) Suggest how the student could reduce their impact.
Part (a) — a concern
disposable batteries, if thrown in general waste, leak toxic chemicals into landfill
the mains heater draws power that may be generated from fossil fuels
→ both carry an environmental cost
Part (b) — reducing impact
recycle the batteries at a designated point, or switch to rechargeable ones
switch off the heater when not in use to save energy
→ naming the concern AND the fix earns the marks
💡 Top tips
- Always pair a precaution with a reason. “Wear goggles” is half an answer; “wear goggles to protect the eyes from splashes” is the full mark
- Keep hazard and risk distinct — examiners notice when you use the words correctly
- For ethics, a justified “no concern” is fine — just say why there’s no issue
- For the environment, always give the fix — identifying an impact without a way to reduce it won’t score
⚠ Common mistakes
- Listing a precaution with no explanation of how it reduces risk
- Using “hazard” and “risk” as if they mean the same thing
- Inventing far-fetched ethical dilemmas — or ignoring a genuine one (like consent for human participants)
- Naming an environmental concern but forgetting to say how you’d reduce the impact
Up next: Measuring Variables in Physics — we’ll go through the right instrument for each quantity (mass, time, length, volume, temperature, current, and more), and how to read each one precisely.
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