IP Physics Notes (Upper Secondary, Year 3-4): 16) Electromagnetic Induction

Study guide30 Sep 2025, 00:00 ZUpdated 16 Jul 2026

Apply Faraday and Lenz, sketch AC generator waveforms, and compute transformer ratios for power transmission questions.

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Q: What does IP Physics Notes (Upper Secondary, Year 3-4): 16) Electromagnetic Induction cover?
A: Apply Faraday and Lenz, sketch AC generator waveforms, and compute transformer ratios for power transmission questions.

Quick recap -- Changing magnetic flux induces emf. Remember: faster change -> larger emf, and the induced current always opposes the flux change (Lenz). Generators and transformers are direct applications.

The core idea is simple: Induction happens when magnetic flux changes.

Use it as a working check: Faster motion, stronger magnets, or more coil turns increase induced emf. Lenz's law says the induced current opposes the change that caused it.

Then go one layer deeper: Use the generator and transformer sections to practise explaining flux change, predicting polarity, sketching AC output, and applying voltage-turns ratios.

Keep your practice loop tight via our Sec 4 IP Physics tuition hub. It links each topic here to quizzes, diagnostics, and WA-style problem sets.

New to the Integrated Programme? Start with What is IP? | Browse all free IP notes.

For Integrated Programme students: Your current school materials, teacher instructions, and assessment scope take precedence because IP topic sequence and depth vary by school. This is an Eclat IP guide, not the O-Level / SEC G3 exam-track guide.

How this chapter applies

Eclat core: induction experiments, Faraday and Lenz reasoning, factors affecting induced e.m.f., the a.c. generator, output graphs, transformer operation, ideal equations, cable losses, and high-voltage transmission follow Marcus Pang's current Chapter 16 route.
Eclat extension depth: magnetic-flux language, detailed transformer loss mechanisms, and additional induction applications deepen the route beyond the minimum K323 wording.
2027 national comparison: K323 Topic 19 overlaps with the full main Eclat sequence.
Check your school: use the current task's expected quantitative form of Faraday's law and transformer assumptions.
Exam-track route: use the separate O-Level and SEC G3 Physics notes for K323 topic ownership.

Faraday's & Lenz's Laws

Faraday: magnitude of induced emf $\mathcal{E}$

Reviewed by

Chee Wei Jie·Academic Advisor (Physics)

Situation	Flux change to name first	Induced face needed	Common trap
North pole moves towards coil	North-going flux through coil increases	Near face becomes north to repel the approach	Saying "opposes the magnet" without naming the increasing flux
North pole moves away from coil	North-going flux through coil decreases	Near face becomes south to attract it back	Using the same current direction as the approach case
South pole moves towards coil	South-going flux through coil increases	Near face becomes south to repel the approach	Forgetting that the pole label flips but the opposition idea stays
Magnet held still inside coil	Flux is not changing	No induced emf or current	Thinking a strong magnet alone is enough for induction

Coil moment	Flux through coil	Rate of change	Graph cue
Coil face is broadside to the field	Maximum or minimum flux	Momentarily zero	Emf crosses zero.
Coil face is edge-on to the field	Flux passes through zero	Greatest rate of change	Emf has maximum magnitude.
Half a turn later	Same orientation but opposite side leading	Same magnitude, opposite direction	Emf has opposite sign.
Faster rotation	Flux pattern repeats more quickly	Greater rate of change	Higher peak emf and higher frequency.

Question clue	First label	Equation move	Trap to avoid
Supply is connected to one coil	That coil is the primary, $p$ .	Put its voltage and turns under $V_p$ and $N_p$ .	Calling the lower-voltage side "primary" just because it is safer.
More turns on secondary	Step-up transformer	$N_s > N_p$ , so $V_s > V_p$
Fewer turns on secondary	Step-down transformer	$N_s < N_p$ , so $V_s < V_p$
Ideal transformer power is assumed	Input power equals output power	Use $V_p I_p = V_s I_s$

IP Physics Notes (Upper Secondary, Year 3-4): 16) Electromagnetic Induction

How this chapter applies

Faraday's & Lenz's Laws

Sources

Induction Setups

Lenz direction checkpoint

Alternating-Current Generator

Generator graph checkpoint

Transformers

Transformer setup checkpoint

Worked Example: Step-Down Calculation

Power Transmission Rationale

Practice Quiz

Key Takeaways

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