Describe a moving conductor induction demonstration
Control conductor, field and motion directions and separate a detector response from a complete generator explanation.
Exam scope and assessment notes
Core and Extended · Physics 0972, 2026–2028. Use the stated source, operating conditions and meter ranges. Written practice is self-checked. Human subject-teacher review, supervised practical competence and cumulative assessment remain pending. Cambridge states that IGCSE 0972 has the same subject content as IGCSE 0625, with 9–1 grading. This StudyForA pathway maps the 2026–2028 syllabus only. This 9–1 graded qualification is available only in a limited number of administrative zones. Confirm that your centre can enter you for this code and exam series with Cambridge International. Cambridge has published a separate syllabus for 2029. StudyForA has not reconciled that version yet; this page supports exams in 2026, 2027 and 2028 only.
Before you begin
- Recognise cross-field conductor movement.
- Distinguish one-factor and two-factor comparisons.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What forms the detector current path in this experiment?
What you will learn
- Control conductor, field and motion directions and separate a detector response from a complete generator explanation.
- Describe a complete controlled detector arrangement and single-factor reversals for moving-conductor induction.
Move the conductor across a field
Place a straight conducting section across a school magnet’s field and connect its ends through suitable flexible leads to a sensitive detector. Move that section across the field while retaining the intended mutually perpendicular geometry. The detector response demonstrates induction; no receiving electrical supply is needed.
Compare motion in one direction with reversed motion, and compare a stationary section with the moving section. Keep detector leads fixed as far as practicable so unintended lead motion does not dominate the reading. The responding circuit includes the moving section and the return leads, not an isolated drawn line.
Interpret controls and measurement limits
Reversing the section’s motion with field and connections fixed reverses the signed response. Reversing the field with motion unchanged also reverses it. Moving along the field gives no corresponding ideal cross-field effect. Direction prediction using the three-direction rule is Supplement; Core observation can describe the sign changes.
Use suitable teacher-supervised apparatus, low-energy magnetic arrangements and secure components. Detector loading and unintended changing circuit area can affect a result. A written method is not evidence of competent physical setup, and a crude response is not a calibrated e.m.f. unless the measurement method establishes it.
Pause and explain
Motion is reversed while field and connections stay fixed. What is the expected signed comparison?
Worked example
Describe a comparison showing that movement direction matters in a conductor demonstration.
Show the worked solution
- Keep field and connections fixed.
- Move the conducting section across the field, then reverse its motion.
- Observe opposite signed responses and compare with a stationary control.
Answer Reverse motion alone and observe sign reversal, with no sustained stationary response.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Specify a moving-conductor demonstration with a stationary comparison.
Give me a hint
Include the field, conductor, detector loop and controlled motion.
Compare my reasoning
- Connect a conductor through leads to a sensitive detector.
- Move its active section across the field in the stated perpendicular geometry.
- Compare response with the stationary section.
Cross-field movement gives a response; the ideal unchanged stationary arrangement does not.
Look for these in your work
- Specify a complete measurement circuit.
- Include a stationary control.
Explain why moving the return leads unpredictably weakens an experiment comparing the active rod’s speeds.
Give me a hint
The rest of the loop can also have changing conditions.
Compare my reasoning
- Lead motion changes parts of the receiving arrangement.
- Their induction contribution can alter the reading.
- Control those leads while comparing the active section.
Uncontrolled lead effects confound the intended speed comparison.
Look for these in your work
- Identify the extra changing factor.
- Describe the control.
A report reverses both rod motion and magnetic field when claiming to test motion reversal alone. Evaluate it.
Give me a hint
A fair single-factor comparison must change only one direction.
Compare my reasoning
- Motion changed.
- Field direction also changed.
- The observed result cannot isolate reversal of motion alone.
The comparison changes two factors; hold field direction fixed to test motion reversal alone.
Look for these in your work
- Name both changes.
- State a corrected comparison.
Common mistakes
- Uncontrolled moving leads can affect readings.
- Keep motion, field and terminal conventions clear.
- Written apparatus planning is not practical competence.
What can you explain now?
What must be kept fixed when testing reversal of motion alone?
Compare with the explanation
Field direction and detector connections
Otherwise a second reversal could cancel or obscure the effect being tested.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Describe a complete controlled detector arrangement and single-factor reversals for moving-conductor induction.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.