Lesson Plan

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Lesson Plan
Grade: Date: 01/12/2025
Subject: Physics
Lesson Topic: use the formula for the combined resistance of two or more resistors in parallel
Learning Objective/s:
  • Describe Kirchhoff’s Current and Voltage Laws and explain their relevance to parallel resistor networks.
  • Derive the parallel‑resistance formula using KCL, KVL and Ohm’s law.
  • Apply the formula to calculate equivalent resistance for two, three, or any number of parallel resistors.
  • Determine total current supplied by a source to a parallel network.
  • Identify and correct common misconceptions when combining resistances in parallel.
Materials Needed:
  • Projector and screen
  • Whiteboard and markers
  • Physics worksheet with derivation and practice problems
  • Calculator for each student
  • Resistor kit (4 Ω, 6 Ω, 12 Ω, etc.)
  • PhET circuit simulation access (or similar)
  • Handout summarising KCL, KVL and the parallel‑resistance formula
 Introduction:
Begin with a real‑world example – why parallel resistors are used in household wiring to ensure each appliance receives the same voltage. Prompt students to recall Ohm’s law and how series resistances are added. State that by the end of the lesson they will be able to derive and use the parallel‑resistance formula correctly.
Lesson Structure:
  1. Do‑Now (5') – quick quiz on series resistance calculations.
  2. Mini‑lecture (10') – review KCL & KVL, then derive the parallel‑resistance formula on the board.
  3. Guided practice (15') – students work through the step‑by‑step derivation in pairs, filling a worksheet.
  4. Simulation activity (10') – use PhET to build parallel circuits, observe equal voltages and total current.
  5. Worked example (10') – teacher solves the 4 Ω, 6 Ω, 12 Ω problem, highlighting common pitfalls.
  6. Independent practice (15') – students complete three practice questions from the handout.
  7. Exit ticket (5') – write the parallel‑resistance formula from memory and one common error to avoid.
Conclusion:
Recap the derivation and emphasise how KCL ensures the total current is the sum of branch currents while KVL guarantees a common voltage. Collect exit tickets to check understanding, and assign homework: complete two additional parallel‑resistor problems and bring any questions for the next class.