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S2 Science: Electric Circuits, Current, Voltage and Resistance (Paper 2: intermediate)
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S2 Science: Electric Circuits, Current, Voltage and Resistance (Paper 2: intermediate)
The usual slips here are treating parallel resistance as a sum and forgetting the watt to kilowatt hour conversion. Remember that in parallel the voltage is shared equally while current splits in inverse proportion to resistance.
Direct answers Answers in order: equal branch voltages, smaller than any branch, 2 ohms, 2 A and 8 V, 24 W, 0.3 kWh, 0.36 dollars, 1 A, 4 ohms, no.
01 Paper details (check answers afterwards)
| Item | Detail |
|---|---|
| Questions | 10 |
| Suggested time | 20 |
| Difficulty mix | Foundation 3 · Intermediate 3 · Challenge 3 · Error redo 1 |
| Chapter | Chapter: S2 Science: Electric Circuits, Current, Voltage and Resistance |
| Level | S2 Science |
02 Questions (10 items)
- FoundationWhat can you say about the voltage on each parallel branch?
- FoundationHow does a parallel total resistance compare with the individual branches?
- IntermediateA 6 ohm and a 3 ohm resistor are in parallel. What is the total resistance?
- IntermediateA 12 V supply is in series with 4 ohm and 2 ohm resistors. Find the current and the voltage across the 4 ohm resistor.
- IntermediateAn appliance runs at 12 V and draws 2 A. What is its power?
- ChallengeA 60 W fan runs for 5 hours. How many kilowatt hours does it use?
- ChallengeIf electricity costs 1.2 dollars per unit, what is the charge for that fan?
- ChallengeTwo lamps are in parallel, each drawing 0.5 A. What current flows in the main branch?
- FoundationA 20 ohm and a 5 ohm resistor are in parallel. What is the total resistance?
- Error redoA student says the total of two parallel resistors is their sum. Is that right?
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | Each branch sees the full supply voltage | Branches meet the same two junctions, so there is no potential difference between them. |
| 2 | Always below the smallest single branch | Each extra path can only lower the combined value. |
| 3 | 2 ohms | Reciprocals give one sixth plus one third, that is one half, so invert to two ohms. |
| 4 | Current 2 A and 8 V across the 4 ohm resistor | Total resistance is six, twelve over six gives two amps, times four gives eight volts. |
| 5 | 24 W | P equals VI, twelve times two is twenty-four. |
| 6 | 0.3 kWh | Sixty times five is three hundred watt hours, which is 0.3 kilowatt hours. |
| 7 | 0.36 dollars | 0.3 times 1.2 is 0.36. |
| 8 | 1 A | The main branch carries the sum of the branches, so 0.5 plus 0.5 is one amp. |
| 9 | 4 ohms | One over one twentieth plus one fifth is four ohms. |
| 10 | No | Adding is the series rule; parallel uses reciprocal addition, giving a total smaller than either resistor. |
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.
Tell the two sameness rules apart: series shares current, parallel shares voltage. For parallel resistance invert the sum of reciprocals; the answer is always below the smallest branch.Tutor Registration →
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.