Lesson Plan

• Describe the construction and function of an iron‑cored transformer.
• Explain how electromagnetic induction produces the induced emf in the primary and secondary windings.
• Apply the turns‑ratio relationship to calculate voltage and current values for ideal transformers.
• Distinguish between ideal and real transformer performance, including core, copper, and leakage losses.
• Analyse a simple transformer problem and determine efficiency estimates.

• Projector or interactive whiteboard with transformer diagram.
• Printed worksheet containing example calculations.
• Small iron‑cored transformer demonstration kit.
• Calculators for each pair of students.
• Whiteboard and markers.
• PowerPoint slides summarising key equations.

Ever wondered how the voltage from a wall outlet can be stepped down to safely charge a phone? Recall Faraday’s law: a changing magnetic field induces an emf in a coil. By the end of the lesson you will be able to explain how a simple iron‑cored transformer works and use the turns‑ratio to solve voltage and current problems.

1. Do‑now (5') – Quick quiz on Faraday’s law displayed on the board.
2. Teacher input (10') – Present basic construction and diagram of an iron‑cored transformer using the projector.
3. Guided inquiry (12') – Demonstrate a small transformer kit; discuss how primary current creates core flux and induces secondary emf.
4. Worked example (10') – Solve the provided example calculation together, highlighting voltage and current ratios.
5. Collaborative practice (10') – Pairs complete worksheet problems, calculating secondary voltage/current for given turn ratios.
6. Concept check (5') – Exit ticket: write the turns‑ratio equation and name one real‑world loss type.
7. Summary (3') – Recap key points and relate them to transformer efficiency.

We revisited how a changing magnetic flux links both windings, producing voltage transformation according to the turns ratio, and considered real‑world losses that reduce efficiency. For the exit ticket, students write an everyday example of a transformer and the associated voltage change. Homework: finish the worksheet on transformer calculations and read the textbook section on core losses.