Electricity, Magnetism & Light — Extension · Science 6: Matter, Energy & Earth Systems, Grade 6
How do fields, circuit paths, and light models explain observable changes? Which modeled circuit keeps lamp B available when lamp A is switched off, and what does the evidence not show?
Design independent lights using circuit evidence
Investigate
Which modeled circuit keeps lamp B available when lamp A is switched off, and what does the evidence not show?
Three 35–45-minute sessions: plan and predict; examine or collect evidence; explain, revise, and reflect. Use the complete supplied record when materials, time, access, or safe conditions are unavailable.
Materials
- The unit’s circuit-path explanation and parallel diagram, plus the complete operation table.
- Paper, colored pencils, and a notebook.
- Optional adult-selected rated low-voltage educational circuit kit; it is not needed to complete the task.
Before you begin
The core investigation is a paper-and-data task. Optional kits must be used only as rated under adult supervision, with dry hands. No wall outlets, loose improvised shorts, dismantled devices, or unapproved power sources are used.
Plan the circuit-model comparison
Compare the defined series and parallel paths with the same ideal source and lamps. Change the specified switch state; record which paths remain complete. Requirements are independent branch control and a common off control; brightness and lifetime are unmeasured.
Method
- State the two operation requirements and draw the supplied model battery, lamps, branches, and switch locations.
- Trace each conducting route with the switches closed. Distinguish charge circulation from energy transfer to lamps.
- For each table row, open the named switch on the paper diagram and identify gaps. Use a rated kit only if a parent has approved that separate method.
- Compare the predicted lamp states with the complete supplied operation record. Record any mismatch in the diagram.
- Recommend the design that meets the two logic requirements and identify unmeasured real performance.
- Revise the diagram to correct one misconception and explain the change using paths and energy rather than charge being used up.
Supplied illustrative record — use when an actual test is unavailable
Illustrative classroom data authored for analysis, not measurements from a real learner, stream, product, or field study. Actual observations may differ; record them honestly and compare the methods.
| Design | Switch state | Lamp A | Lamp B |
|---|---|---|---|
| Series | Main closed | On | On |
| Series | A-path switch open | Off | Off |
| Parallel | Both branches and common closed | On | On |
| Parallel | A branch open, B/common closed | Off | On |
| Parallel | B branch open, A/common closed | On | Off |
| Parallel | Common open | Off | Off |
Analyze and explain
- Which design satisfies independent branch control? Explain a complete remaining path.
- Why can a common switch still stop both lamps?
- What happens to charge and energy at a lamp?
- Which real-device judgments would require additional evidence?
What a strong explanation includes
- Correct path tracing for every supplied switch condition.
- Independent and common control distinguished.
- Energy transfer separated from charge consumption.
- A reasoned diagram revision.
- Ideal logic separated from actual brightness, life, and safety.
Parent / teacher guide: discuss after the investigation
The supplied parallel design meets independent branch control: with A’s branch open, B still has a complete route through its branch and the common source connections. The series design does not meet that requirement because opening its shared path interrupts both lamps. In the parallel design, opening the common switch interrupts every branch’s route, satisfying the common-off requirement. The explanation concerns connection logic. A lamp receives energy and transfers it into light and thermal changes; it does not consume all charge so the return path becomes empty. Correctly tracing the return connection is therefore part of explaining both designs. A diagram with arrows disappearing at the first lamp would misrepresent the model even if its lamp labels happened to be correct. This record does not compare brightness, source lifetime, component heating, or the safety of an improvised real device. Those depend on actual components and ratings, not just a paper loop. The optional kit follows its manufacturer’s approved setup and can have results different from the ideal model. A useful revision might relocate a switch from the common path into a branch, then recheck every row to confirm the intended control and note that the revised real design would still need approved testing.
Compare this model with the learner’s actual evidence. Different measurements can support a different conclusion; check the reasoning and limitations, not matching wording.
Extend the chapter investigation by evaluating its evidence and proposing a better test.
Problem 1
Answer and explanation
The supplied parallel design meets independent branch control: with A’s branch open, B still has a complete route through its branch and the common source connections. The series design does not meet that requirement because opening its shared path interrupts both lamps. In the parallel design, opening the common switch interrupts every branch’s route, satisfying the common-off requirement. The explanation concerns connection logic. A lamp receives energy and transfers it into light and thermal changes; it does not consume all charge so the return path becomes empty. Correctly tracing the return connection is therefore part of explaining both designs. A diagram with arrows disappearing at the first lamp would misrepresent the model even if its lamp labels happened to be correct. This record does not compare brightness, source lifetime, component heating, or the safety of an improvised real device. Those depend on actual components and ratings, not just a paper loop. The optional kit follows its manufacturer’s approved setup and can have results different from the ideal model. A useful revision might relocate a switch from the common path into a branch, then recheck every row to confirm the intended control and note that the revised real design would still need approved testing.
Problem 2
Answer and explanation
The supplied parallel design meets independent branch control: with A’s branch open, B still has a complete route through its branch and the common source connections. The series design does not meet that requirement because opening its shared path interrupts both lamps. In the parallel design, opening the common switch interrupts every branch’s route, satisfying the common-off requirement. The explanation concerns connection logic. A lamp receives energy and transfers it into light and thermal changes; it does not consume all charge so the return path becomes empty. Correctly tracing the return connection is therefore part of explaining both designs. A diagram with arrows disappearing at the first lamp would misrepresent the model even if its lamp labels happened to be correct. This record does not compare brightness, source lifetime, component heating, or the safety of an improvised real device. Those depend on actual components and ratings, not just a paper loop. The optional kit follows its manufacturer’s approved setup and can have results different from the ideal model. A useful revision might relocate a switch from the common path into a branch, then recheck every row to confirm the intended control and note that the revised real design would still need approved testing.
Problem 3
Answer and explanation
The supplied parallel design meets independent branch control: with A’s branch open, B still has a complete route through its branch and the common source connections. The series design does not meet that requirement because opening its shared path interrupts both lamps. In the parallel design, opening the common switch interrupts every branch’s route, satisfying the common-off requirement. The explanation concerns connection logic. A lamp receives energy and transfers it into light and thermal changes; it does not consume all charge so the return path becomes empty. Correctly tracing the return connection is therefore part of explaining both designs. A diagram with arrows disappearing at the first lamp would misrepresent the model even if its lamp labels happened to be correct. This record does not compare brightness, source lifetime, component heating, or the safety of an improvised real device. Those depend on actual components and ratings, not just a paper loop. The optional kit follows its manufacturer’s approved setup and can have results different from the ideal model. A useful revision might relocate a switch from the common path into a branch, then recheck every row to confirm the intended control and note that the revised real design would still need approved testing.
Problem 4
Answer and explanation
The supplied parallel design meets independent branch control: with A’s branch open, B still has a complete route through its branch and the common source connections. The series design does not meet that requirement because opening its shared path interrupts both lamps. In the parallel design, opening the common switch interrupts every branch’s route, satisfying the common-off requirement. The explanation concerns connection logic. A lamp receives energy and transfers it into light and thermal changes; it does not consume all charge so the return path becomes empty. Correctly tracing the return connection is therefore part of explaining both designs. A diagram with arrows disappearing at the first lamp would misrepresent the model even if its lamp labels happened to be correct. This record does not compare brightness, source lifetime, component heating, or the safety of an improvised real device. Those depend on actual components and ratings, not just a paper loop. The optional kit follows its manufacturer’s approved setup and can have results different from the ideal model. A useful revision might relocate a switch from the common path into a branch, then recheck every row to confirm the intended control and note that the revised real design would still need approved testing.