SPI Physics · Free notes
Energy Sources: SPI Physics
Energy Sources has 8 questions in the SPI bank, three from Practice Paper 1 and five from the LWS mocks, and none from the 2022 paper. Seven are EASY and one is MODERATE, and not one needs a calculation: each asks for a single fact about a source. The wrong options are built from half-truths, such as nuclear power counted as clean because it gives no smoke, so these pages give each source its drawback alongside its energy chain.
The handout has every subtopic, worked example, formula and trap with answers shown. The formula sheet is the chapter’s formulas and traps alone, on one page.
Subtopic notes
Power Plants and Clean Energy
5 questionsA power plant changes one form of energy into electrical energy, and a source is clean when using it gives out no smoke, harmful gases or dangerous waste.
Biomass and Biogas
3 questionsBiomass is fuel from the bodies and waste of plants and animals, and biogas is the gas that bacteria make from it when they break it down without air.
Formula & revision sheet
0 formulas · 5 reference tables · 10 gotchas across all subtopics — the exam-eve cheat-sheet
Formula & revision sheet
0 formulas · 5 reference tables · 10 gotchas across all subtopics — the exam-eve cheat-sheet
Reference tables (3)
The chain of energy changes in each power plant5 rows
| Plant or device | Energy at the start | Chain of changes |
|---|---|---|
| Thermal power plant | Chemical energy of coal | chemical → heat → kinetic (turbine) → electrical |
| Nuclear power plant | Nuclear energy of uranium | nuclear → heat → kinetic (turbine) → electrical |
| Hydroelectric plant | Potential energy of stored water | potential → kinetic → electrical |
| Wind mill generator | Kinetic energy of wind | kinetic → electrical |
| Solar cell | Light energy of the Sun | light → electrical |
Clean and polluting sources, and the drawback of each7 rows
| Source | Clean while making energy? | Main drawback |
|---|---|---|
| Solar | Yes, the least polluting | Weak at night and on cloudy days |
| Wind | Yes | Needs steady strong winds and a lot of land |
| Tidal | Yes | Few coastal sites are suitable |
| Hydroelectric (dam) | Yes, no fuel is burnt | Floods land and harms the plants and animals of the region |
| Geothermal | Mostly | Can release gases such as hydrogen sulphide |
| Nuclear | No | Radioactive waste and the risk of radiation leaks |
| Thermal (coal) | No | Smoke, carbon dioxide and other gases |
Solar cells and what they are made of5 rows
| Question | Answer |
|---|---|
| Energy change in a solar cell | Light energy into electrical energy |
| Kind of material | Semiconductor |
| Elements used | Silicon (most common), selenium (earliest cells) |
| Many cells joined together | A solar panel |
| Common uses | Satellites, road signs, calculators |
Watch out for (5)
- Putting electrical energy in the middle→ The chain of energy changes in each power plant
- Skipping the heat step in a nuclear plant→ The chain of energy changes in each power plant
- Calling nuclear energy clean because it gives no smoke→ Clean and polluting sources, and the drawback of each
- Saying a dam pollutes the air→ Clean and polluting sources, and the drawback of each
- Picking a familiar metal→ Solar cells and what they are made of
Reference tables (2)
What counts as biomass, and how biogas forms7 rows
| Fuel | Biomass? | Why |
|---|---|---|
| Wood | Yes | Comes from trees |
| Cow dung cakes | Yes | Animal waste |
| Crop waste | Yes | Plant material |
| Gobar gas (biogas) | Yes | Made by bacteria from dung and plant waste |
| Coal | No | A fossil fuel, buried for millions of years |
| Petroleum | No | A fossil fuel |
| Uranium (nuclear fuel) | No | Not from living matter at all |
The biogas plant: what goes in and what comes out7 rows
| Part of the process | What it is |
|---|---|
| Goes in | Slurry of dung (or plant waste) and water |
| Conditions | Water present, air kept out |
| Closed tank | The digester |
| Main gas made | Methane |
| Other gases | Carbon dioxide, hydrogen, hydrogen sulphide |
| Left behind | Slurry used as manure, rich in nitrogen and phosphorus |
| Uses of the gas | Cooking and lighting |
Watch out for (5)
- Calling coal biomass→ What counts as biomass, and how biogas forms
- Choosing aerobic respiration for biogas→ What counts as biomass, and how biogas forms
- Thinking the digester needs fresh air→ The biogas plant: what goes in and what comes out
- Forgetting the water→ The biogas plant: what goes in and what comes out
- Calling carbon dioxide the main gas→ The biogas plant: what goes in and what comes out
Question weightage by concept
5 concepts · 8 questions — where the marks actually sit, so you know what to drill first
Question weightage by concept
5 concepts · 8 questions — where the marks actually sit, so you know what to drill first
| Concept | Qs | Share |
|---|---|---|
| Clean and polluting sources, and the drawback of each | 3 | 38% |
| The chain of energy changes in each power plant | 1 | 13% |
| Solar cells and what they are made of | 1 | 13% |
| Concept | Qs | Share |
|---|---|---|
| What counts as biomass, and how biogas forms | 2 | 25% |
| The biogas plant: what goes in and what comes out | 1 | 13% |
Test yourself on a real paper
Sit a past SPI paper, timed and marked the way the exam marks it. You see your score and every answer the moment you finish. Free to start.