Lesson Plan

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Lesson Plan
Grade: Date: 17/01/2026
Subject: Physics
Lesson Topic: Describe the action of a variable potential divider
Learning Objective/s:
  • Describe how a variable potential divider adjusts output voltage using the wiper position.
  • Explain the difference between potentiometers and rheostats and their typical applications.
  • Calculate the output voltage for a given wiper position and supply voltage, accounting for load effects.
  • Demonstrate correct wiring and safe use of a variable potential divider in a circuit.
Materials Needed:
  • Potentiometer (or rheostat) kit
  • DC power supply (e.g., 12 V)
  • Multimeter or voltmeter
  • Resistive load (lamp or resistor)
  • Connecting wires and breadboard
  • Projector or whiteboard for diagrams
  • Worksheet with calculation exercises
 Introduction:
Begin with a quick demonstration of a lamp whose brightness changes as the potentiometer is turned, asking students what is happening. Recall the basic voltage‑divider formula and how resistance ratios affect voltage. Explain that today they will explore how moving the wiper provides a controllable voltage and identify the success criteria.
Lesson Structure:
  1. Do‑now (5'): Students sketch a simple voltage divider and label Vs, R1, R2.
  2. Mini‑lecture (10'): Explain the principle of a variable potential divider, show Vout = Vs(1‑x/L), and differentiate potentiometer vs rheostat.
  3. Guided demonstration (10'): Connect a potentiometer to a 12 V supply, vary the wiper, and measure Vout while discussing load effect.
  4. Collaborative calculation activity (15'): Pairs complete worksheet problems calculating Vout for given positions and load resistances.
  5. Concept check (5'): Quick quiz using clickers or show of hands on key concepts.
  6. Summary discussion (5'): Review key points and answer lingering questions.
Conclusion:
Summarise that the wiper position linearly controls output voltage when the load resistance is much larger than the track resistance, and emphasise the impact of load effects. Ask students to write one real‑world example of a device that uses a variable potential divider as an exit ticket. Assign homework to design a simple circuit using a potentiometer to set LED brightness.