Technological applications of physics: impact on science, society and the environment
You are driving along the coast of Mayo and pass a row of wind turbines. One passenger says, "They're a great way to make clean electricity." Another says, "They spoil the view and they don't turn when the wind drops." Who is right?
Both have a point. Most technologies have benefits and drawbacks, and a scientist's job is to look at the evidence and judge fairly. This page shows you how to do that, and how to back it up with numbers. At the end we come back to the wind farm.
Technology, and three kinds of impact
Technology is the use of scientific knowledge to solve a problem or to make something useful. Many technologies come from physics: wind turbines (energy), mobile phones (waves), X-ray machines (radiation) and LED bulbs (electricity).
When you are asked about the impact of a technology, think about three areas.
An impact can be positive (a benefit) or negative (a drawback). A good answer names which kind it is and gives a reason.
| Technology | Scientific impact | Social impact | Environmental impact |
|---|---|---|---|
| Wind turbine | Better understanding of wind resources | Jobs and cheaper electricity, but some people object to the view and the noise | No CO₂ while running, but can affect birds and bats |
| Mobile phone | Data from satellites and sensors can be shared instantly | Easy communication, but screen time and privacy worries | Mining of metals for phones, and electronic waste |
| MRI scanner | Allows study of the brain and body without surgery | Earlier diagnosis, but expensive and in demand | Uses a lot of electricity |
Energy technologies: wind, solar and storage
Ireland has a lot of wind, especially on the west coast. Wind turbines transform the kinetic energy of moving air into electrical energy. Solar panels (photovoltaic panels) transform light energy into electrical energy.
| Benefits | Drawbacks | |
|---|---|---|
| Wind | No CO₂ or smoke while running. Free fuel. Land underneath can still be farmed. | Output varies with the wind. Visual and noise concerns for neighbours. Can harm birds and bats. |
| Solar | No CO₂ while running. Quiet. Can be fitted to existing roofs. | Output is low on dull days and zero at night. Making the panels uses energy and materials. |
| Burning peat or coal | Steady output that can be switched up or down. | Releases a lot of CO₂ and other pollutants. The fuel runs out. Bogs lose habitat. |
Wind and solar output goes up and down with the weather. What happens when the wind drops and there is no sun? One answer is energy storage. A pumped-storage station, such as Turlough Hill in Co. Wicklow, works like a giant rechargeable battery.
The energy changes are:
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Surplus electricity → pumps water uphill → gravitational potential energy of the water.
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High demand → water runs down → kinetic energy → turns a turbine → electrical energy.
Some energy is always lost as heat, so you get back less than you put in. But storing energy lets the system cope when wind and solar output are low.
Wind turbines are used on the west coast of Ireland to generate electricity. Name one benefit and one drawback of wind energy for the environment or for local people.
Wind turbines are used on the west coast of Ireland to generate electricity. Name one benefit and one drawback of wind energy for the environment or for local people.
Solar panels are fitted to the roof of a school. State the energy transformation that occurs in a solar panel and name one advantage of using solar panels compared with…
Solar panels are fitted to the roof of a school. State the energy transformation that occurs in a solar panel and name one advantage of using solar panels compared with burning fossil fuels.
Calculating energy, savings and output
You need three ideas from earlier in the course.
Why $E = Pt$? Power is the energy used each second (or each hour). The longer a device runs, the more energy it uses.
Wind farms are rated by their maximum power, but the wind does not always blow at full strength. The average output is a percentage of the maximum, so we use:
$$\text{average power} = \text{maximum power} \times \frac{\text{percentage}}{100}$$A household replaces five $60\ \text{W}$ filament bulbs with five $8\ \text{W}$ LED bulbs. Each is used for $4$ hours per day. a) Calculate the energy saved per day in…
A household replaces five $60\ \text{W}$ filament bulbs with five $8\ \text{W}$ LED bulbs. Each is used for $4$ hours per day.
- a) Calculate the energy saved per day in kWh.
- b) Calculate the saving per year ($365$ days) if electricity costs €0.30 per kWh.
- c) Suggest one environmental benefit of this change.
A community near Limerick is considering a new wind farm of $10$ turbines, each with a power output of $3.0\ \text{MW}$ when running. The turbines operate at an average…
A community near Limerick is considering a new wind farm of $10$ turbines, each with a power output of $3.0\ \text{MW}$ when running. The turbines operate at an average of $35\%$ of their maximum output.
- a) Calculate the maximum power of the whole wind farm in MW.
- b) Calculate the average power output in MW.
- c) Calculate the energy produced in one day in MWh.
- d) Discuss one social and one environmental issue the community should consider.
Communication technology
Mobile phones, Wi-Fi and satellite navigation all depend on electromagnetic waves (radio waves and microwaves). These waves travel at the speed of light:
$$c = 3.0 \times 10^{8}\ \text{m s}^{-1}$$To find how long a signal takes, use speed = distance ÷ time, rearranged:
$$t = \frac{d}{v}$$Signals travel very fast, so the delay is tiny. That is why you can have a video call with someone in another country.
Impacts of mobile technology:
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Scientific: sensors and phones collect and share data quickly, for example weather and citizen-science records.
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Social: people can contact each other and call emergency services from almost anywhere, but there are concerns about screen time, privacy and cyberbullying.
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Environmental: phones need metals that are mined, and old phones become electronic waste unless recycled. Masts and data centres use electricity.
Mobile phone technology has changed how people communicate. Phones use electromagnetic waves, travelling at $3.0 \times 10^{8}\ \text{m/s}$. a) Calculate the time for a…
Mobile phone technology has changed how people communicate. Phones use electromagnetic waves, travelling at $3.0 \times 10^{8}\ \text{m/s}$.
- a) Calculate the time for a signal to travel $300\ \text{km}$ from a mast to a phone.
- b) State one scientific, one social and one environmental impact of mobile phone technology.
Physics in medicine
Hospitals use many technologies based on physics. These are some you should know.
| Technology | Physics used | How it helps |
|---|---|---|
| X-ray | Ionising radiation passes through soft tissue but is absorbed by bone | Shows broken bones and some chest problems |
| MRI scan | Strong magnetic field and radio waves | Detailed images of soft tissue such as the brain and joints, with no ionising radiation |
| Ultrasound | High-frequency sound waves reflected from tissues | Safe images of a baby before birth |
| Radiotherapy | Ionising radiation aimed at a tumour | Destroys cancer cells |
Why ionising radiation carries risk
Ionising radiation (such as X-rays and gamma rays) has enough energy to damage atoms and molecules in living cells. It can damage DNA. A damaged cell may die, or it may start to divide in an uncontrolled way, which can lead to cancer. The risk rises with the dose.
For this reason X-rays are used only when the benefit outweighs the risk, and doctors use the lowest dose that works. Staff stand behind a screen or wear lead aprons, because lead absorbs X-rays.
Comparing X-ray and MRI
| X-ray | MRI | |
|---|---|---|
| Radiation | Ionising: small risk | Not ionising |
| Speed | Very quick | Long scan, noisy, and the patient must lie still |
| Cost | Cheaper, widely available | Expensive, fewer machines |
| Best for | Broken bones, emergencies | Brain, spinal cord, soft tissue |
| Safety limits | Limit the number of scans | Strong magnet: not suitable for some metal implants or pacemakers |
Who gets the scan?
Scanners are expensive and there are not enough for everyone straight away. This raises ethical questions: should the person who is sickest go first, or the person who can pay? Should we scan people with no symptoms? These questions have no single right answer. You must give reasons.
Name two technologies based on physics that are used in medicine (for example in a hospital in Dublin) and state one way each helps patients.
Name two technologies based on physics that are used in medicine (for example in a hospital in Dublin) and state one way each helps patients.
X-rays and MRI scans are widely used in hospitals. X-rays use ionising radiation; MRI uses magnetic fields and radio waves. a) Explain why ionising radiation carries a…
X-rays and MRI scans are widely used in hospitals. X-rays use ionising radiation; MRI uses magnetic fields and radio waves.
- a) Explain why ionising radiation carries a risk and why X-ray exposure is limited.
- b) Compare the two technologies in terms of benefits and risks, identifying one situation where each is more appropriate.
- c) Discuss one ethical or cost-related issue that arises when deciding who receives scans.
Evaluating a technology
To evaluate a technology means to weigh up the evidence and reach a justified conclusion. Follow these steps.
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List the benefits and drawbacks, using the three headings: scientific, social, environmental.
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Use evidence: numbers, such as CO₂ emitted, cost or energy produced.
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Consider who is affected: neighbours, workers, future generations.
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Check the source: is it independent, or does it come from a company or a campaign group with its own interest?
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Conclude and say what extra information would help.
Notice that the electric car is not "zero emission". The emissions move from the exhaust to the power station. As more wind and solar power is added, the figure for electricity falls.
Coming back to the wind farm
We started with two passengers arguing about wind turbines. Now you can answer with evidence. Wind turbines produce no CO₂ while running, so they cut emissions compared with peat or gas, but their output varies, so storage or back-up is needed. Some neighbours object to the view and noise, and birds can be affected. A fair evaluation gives both sides and says what more information is needed.
A power station burns peat to produce electricity. A proposal suggests replacing it with a combination of wind and solar power plus a pumped-storage hydroelectric plant.…
A power station burns peat to produce electricity. A proposal suggests replacing it with a combination of wind and solar power plus a pumped-storage hydroelectric plant.
- a) Explain the role of pumped storage in dealing with the variable output of wind and solar.
- b) Evaluate the proposal, giving two environmental and two social advantages and disadvantages.
- c) State what additional information you would need to make a fully informed decision.
An electric car has a battery of capacity $60\ \text{kWh}$ and travels $400\ \text{km}$ on a full charge. A petrol car uses $6.0$ litres per $100\ \text{km}$ and petrol…
An electric car has a battery of capacity $60\ \text{kWh}$ and travels $400\ \text{km}$ on a full charge. A petrol car uses $6.0$ litres per $100\ \text{km}$ and petrol releases about $2.3\ \text{kg}$ of $\text{CO}_2$ per litre. Assume electricity in Ireland produces $0.30\ \text{kg}$ of $\text{CO}_2$ per kWh.
- a) Calculate the $\text{CO}_2$ emitted by the petrol car per $100\ \text{km}$.
- b) Calculate the $\text{CO}_2$ attributable to electricity for the electric car per $100\ \text{km}$.
- c) Discuss, with reasons, whether the electric car is better for the environment, mentioning one factor not included in your calculation.