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Primary General Studies, Science and Technology, Paper 3: electromagnets, conductors and heat
Primary General Studies, Science and Technology, Paper 3: electromagnets, conductors and heat
Ten items on electromagnets losing magnetism, conductors and insulators, refraction, series circuits, cells in series, same-direction forces, conservation of mass, power in kWh and heat conduction.
Focus An electromagnet is magnetic only while current flows; metals conduct and plastic insulates; light bends leaving water; one break stops a series circuit; series voltages add; same-direction forces add; dissolving keeps total mass; kWh is kW times hours; denser than water sinks; metal conducts heat fastest.
01 Paper details (check answers afterwards)
| Item | Detail |
|---|---|
| Questions | 10 |
| Suggested time | 25 |
| Difficulty mix | Foundation 4 · Intermediate 3 · Challenge 2 · Error redo 1 |
| Chapter | Chapter: Primary General Studies: Science and Technology |
| Level | P4 to P6 |
02 Questions (10 items)
- FoundationWhat happens to an electromagnet when its battery is taken away?
- FoundationWhich of these lets electricity pass through?
- FoundationA chopstick standing in a glass of water looks bent. What is this?
- FoundationTwo bulbs are joined in series and one breaks. What happens to the other?
- IntermediateThree 1.5 V cells are joined in series. What is the total voltage?
- IntermediateForces of 15 N and 9 N pull in the same direction. What is the resultant force?
- Intermediate100 g of water dissolves 50 g of salt completely. What is the mass of the salt water?
- ChallengeA 40 W lamp is left on for 5 hours. How many units (kWh) does it use?
- ChallengeA stone has a mass of 50 g and a volume of 25 cm³. Find its density and say whether it sinks.
- Error redoA wooden spoon and a metal spoon go into hot soup. Which gets hot faster?
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | It loses its magnetism and the iron nail it holds drops off. | An electromagnet is magnetic only while current flows. |
| 2 | A copper coin, because it is metal. | Metals such as copper and iron conduct; plastic and wood insulate. |
| 3 | Refraction of light. | Light changes direction on leaving water, so the stick only looks bent. |
| 4 | It goes out too, because the whole circuit is broken. | A series circuit has one path, so any break stops the current everywhere. |
| 5 | 4.5 V. | In series the voltages add up: 3 x 1.5 = 4.5 V. |
| 6 | 24 N in the same direction. | Forces in the same direction add; opposite ones subtract. |
| 7 | 150 g. | Dissolving keeps every gram, so total mass is conserved: 100 + 50 = 150 g. |
| 8 | 0.2 kWh. | Units equal power in kW times hours: 40 / 1000 x 5 = 0.2 kWh. |
| 9 | 2 g/cm³, which is denser than water, so it sinks. | Density is mass over volume: 50 / 25 = 2 g/cm3, and water is 1 g/cm3. |
| 10 | The metal spoon, because metal conducts heat well. | A common mistake is thinking wood carries heat faster; metal conducts best, which is why pan handles are wood or plastic. |
04 What to do after marking
- After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
- Repeat the same item two days later; move to the next paper only when both attempts are correct.
- Parents only need the answer and note columns; there is no need to explain every item.
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Questions and answers are written originally by the TutorZone team and are not taken from any school, publisher or examination authority paper. Every value is checked by computer.
