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S5 Physics: Circuits Practice Paper 2
S5 Physics: Circuits Practice Paper 2
Paper two starts with series addition and the parallel reciprocal rule, then Ohm law and power, then voltage division and branch currents, then three-resistor parallel networks and a parallel-then-series mixed circuit, ending with the add-parallel-resistances trap.
Quick answer 12 ohm, 4 ohm, 4 A and 80 W, 12 V and 48 W, 2 A with 8 V and 12 V, 6 ohm and 2 A, 7 ohm and 2 A, 2 ohm and 6 A, 9 ohm with 2 A and 0.5 A and 1.5 A, and 8 ohm being wrong.
01 Paper details (check answers afterwards)
| Item | Detail |
|---|---|
| Questions | 10 questions |
| Suggested time | 25 minutes |
| Difficulty mix | Foundation 4 · Intermediate 3 · Challenge 2 · Error redo 1 |
| Chapter | Chapter: S5 Physics: Circuits – Tutor Lesson Plan |
| Level | S5 |
02 Questions (10 items)
- FoundationA 5 ohm and a 7 ohm resistor are connected in series. Find the equivalent resistance.
- FoundationA 12 ohm and a 6 ohm resistor are in parallel. Find the equivalent resistance.
- FoundationA 20 V supply drives a 5 ohm resistor. Find the current and the power.
- FoundationA current of 4 A flows through a 3 ohm resistor. Find the voltage across it and the power.
- IntermediateA 20 V supply is in series with a 4 ohm and a 6 ohm resistor. Find the current and each voltage.
- IntermediateA 10 ohm and a 15 ohm resistor in parallel are connected to 12 V. Find the equivalent resistance, total and branch currents.
- IntermediateTwo 4 ohm resistors in parallel are in series with a 5 ohm resistor across 14 V. Find the equivalent resistance and total current.
- ChallengeThree resistors of 6 ohm, 12 ohm and 4 ohm are in parallel across 12 V. Find the equivalent resistance and total current.
- ChallengeA 18 V supply feeds 6 ohm in series with a 12 ohm and 4 ohm parallel pair. Find the equivalent resistance, total current, the parallel-section voltage and both branch currents.
- Error redoTwo 4 ohm resistors are in parallel and a student answers “4 + 4 = 8 ohm”. What is correct?
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | 12 ohm. | Series resistances simply add. |
| 2 | 4 ohm. | Add reciprocals then invert; the result is always below the smaller resistor. |
| 3 | 4 A and 80 W. | Use I = V / R first, then P = V times I. |
| 4 | 12 V and 48 W. | V = I R and P = I squared R follow from the same substitution. |
| 5 | Current 2 A, 8 V across the 4 ohm and 12 V across the 6 ohm. | Series current is shared equally while the voltage splits in proportion to resistance. |
| 6 | Equivalent 6 ohm, total current 2 A, branch currents 1.2 A and 0.8 A. | Branches share the same voltage, so find each branch current then add. |
| 7 | Equivalent 7 ohm, total current 2 A. | Simplify the parallel pair to 2 ohm first, then add the series part. |
| 8 | Equivalent 2 ohm, total current 6 A. | With three or more, still add reciprocals; the answer is below the smallest, 4 ohm. |
| 9 | Equivalent 9 ohm, total current 2 A, 6 V across the parallel section, branch currents 0.5 A and 1.5 A. | The parallel pair is 3 ohm, so the total is 9 ohm; then work back layer by layer. |
| 10 | 2 ohm. | Parallel resistances do not add: two equal resistors give exactly half the value. |
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.
