Lesson Plan

• Recall the voltage‑turns ratio equation for an ideal transformer.
• Explain how the turns ratio determines the change in voltage and current between primary and secondary windings.
• Apply the equation to calculate secondary voltage and current for step‑up and step‑down transformers.
• Identify common mistakes when using the ratio and recognise the limits of the ideal‑transformer model.

• Projector and screen
• PowerPoint slide with transformer diagram
• Printed handout of the voltage‑turns ratio equation and example problems
• Worksheet for independent practice
• Calculators
• Mini‑transformer models (optional demonstration)

Begin with a quick question: “Why does a phone charger change the voltage from the wall socket?” Connect this to students’ prior knowledge of voltage and current in circuits. State that by the end of the lesson they will be able to use the transformer ratio equation to predict voltage and current changes and check their work against a clear success criterion.

1. Do‑now (5'): Short quiz on primary vs. secondary coils and basic circuit symbols.
2. Mini‑lecture (10'): Introduce the transformer, show the cross‑section diagram, and define primary/secondary windings.
3. Derivation walk‑through (10'): Use Faraday’s law to derive Vₚ/Vₛ = Nₚ/Nₛ and discuss power conservation.
4. Guided practice (15'): Solve the worked example together, highlighting each step of the calculation.
5. Independent practice (15'): Students complete worksheet problems on step‑up and step‑down transformers.
6. Check for understanding (5'): Exit‑ticket – write the correct form of the ratio and one common mistake to avoid.

Summarise how the turns ratio controls voltage and current, reinforcing the power‑conservation idea. Collect exit‑tickets to gauge mastery and assign a short homework task: calculate the secondary voltage for a given transformer using the ratio.